Another undeniable fact can be trotted out in support of such a scenario. All six previous Grand Finals have featured the teams finishing the regular season in first or second place as Leinster and Connacht have just done.
Nobody from as far afield as third or fourth has ever got to the Grand Final, all of which will strengthen the collective resolve of the Warriors and Ulster that there is a first time for everything and that time will be next weekend.
In the best of all Glasgow worlds, the holders would have had the comfort of defending their title on familiar territory beside the Clyde instead of having to make a swift return to the Atlantic shore where their nine-match winning streak went west last Saturday.
While Ulster would naturally have preferred a home tie rather than heading down the familiar road to Dublin, they, like the Warriors, will not lose any sleep over the outcome of semi-finals long consigned to the dustbin of history.
On the contrary, they will fancy their chances of proving the old diktat attributed to Henry Ford, the Cork migrant's son who put America on wheels, that all history is bunk.
Since losing in Glasgow at the end of March, Ulster have swept all before them. Theirs has been a majestic charge into the play-offs, denying Connacht the small consolation of a losing bonus point, then outplaying Leinster to win by the length of Royal Avenue before hitting Ospreys for six tries in Swansea last weekend.
Ulster are undeniably playing their best rugby of the season at the very time when it matters most and yet Connacht are still defying the odds, still reaching new frontiers in their wonderful climb from nobodies to potential champions, still the story of the Guinness PRO12 season.
There is a magnetism about them which perhaps explains why the great and the good are drawn irresistibly to join the bulging support. The President of Ireland, Michael D Higgins, and the Taoiseach Enda Kenny saw the victory over the Warriors for themselves.
Such Presidential and Prime Ministerial presence had not been seen at the Sportsground before. Had the teenaged John Muldoon talked about that happening when he first turned up there around the turn of the century, he would have been dismissed as being away with the fairies.
Over the last nine months, Muldoon has turned the fairytale into inspiring reality. At the Guinness Storehouse in Dublin last Sunday during an awards ceremony which captured the unique international flavour of the Guinness PRO12, Connacht's enduring captain won special acclaim.
There can never have been a worthier winner of the Chairman's Award, as presented by a man who will forever reside at the centre of rugby's Magic Circle, Gerald Davies. The Welsh wizard paid due tribute to Muldoon as 'a terrific team man and all-round good guy.'
In a sport where players move from club to club with increasing frequency, Muldoon has stayed put on home territory, the ultimate one-team. ''I've been a professional at Connacht for 13 years and I was training with them for two years before that,'' he said. ''It's changed massively during that time.
''The ground, for example, was always known as the 'Dog Track.' Now it's known as the home of Connacht rugby. In my first year we played Harlequins in the semi-final of the European Challenge Cup and we didn't have a groundsman or anybody. So there were yellow flowers on the pitch.
''We used to get 400 coming to the games back then. Now we're full to capacity for every match. That says everything about how it's changed.
''A lot of GAA fans come to see us now. That's grand and their knowledge of the rules is improving so maybe they'll be giving the referees less abuse! In days gone by you'd see a lot of Munster and Leinster jerseys around the place but they've all been put away. Everyone's wearing Connacht jerseys now.
''New clubs are popping up all over the place. Young fellas want to play rugby and enjoy it. They want to be Bundee Aki. With the bigger crowds there's been some talk about moving to a bigger stadium but the Sports Ground is a hard place for teams to come. We don't want to be moving out of it.'
Muldoon's recognition, Aki's choice as Player of the Year and Pat Lam's anointment as Coach of the Year completed Connacht's take-over of the podium, a one, two, three greeted by unanimous approval from their rivals.
Lam had made the longest haul any New Zealander can make, to the western edge of Europe not that he knew exactly where he was headed after finishing with the Auckland Blues.
''I had to look on the map,'' he said. ''I had no idea where Galway was or that Connacht consisted of counties like Roscommon, Mayo and Sligo.
''I'm a big vision dream person and blessed to be in an organisation which has a clear vision. Our awards night in Connacht was a celebration of everything that is good about rugby in western Ireland.''
If they are to clear the last obstacle standing between them and the Grand Final, Connacht will have to beat the Warriors for the second time in a row and nobody's done that since Gregor Townsend galvanised them into the most consistent performers in the tournament.
Nobody does semi-finals on quite the same exhilarating scale as the Guinness PRO12. For all the home supremacy, there have been many desperately close-run duels, as the record shows.
Guinness PRO12 play-off semi-finals season by season:
2009-10:
Leinster (1st) 16, Munster (4th) 6 (at the RDS)
Ospreys (2nd) 20, Glasgow Warriors (3rd) 6 (at the Liberty Stadium).
2010-11:
Munster (1st) 18, Ospreys (4th) 11 (at Thomond Park)
Leinster (2nd) 18, Ulster (3rd) 3 (at the RDS)
2011-12:
Leinster (1st) 19, Glasgow Warriors (4th) 15 (at the RDS)
Ospreys (2nd) 45, Munster (3rd) 10 (at the Liberty Stadium)
2012-13:
Ulster (1st) 28, Scarlets (4th) 17 (at Ravenhill)
Leinster (2ND) 17, Glasgow Warriors (3rd) 15 (at the RDS).
2013-14:
Leinster (1st) 13, Ulster (4th) 9 (at the RDS)
Glasgow Warriors (2nd) 16, Munster (3rd) 15 (at Scotstoun)
2014-15:
Glasgow Warriors (1st) 16, Ulster (4th) 14 (at Scotstoun)
Munster (2nd) 21, Ospreys (3rd) 18 (at Thomond Park)
2015-16:
Leinster (1st) v Ulster (4th) at the RDS
Connacht (2nd) v Glasgow Warriors at the Sports Ground, Galway.
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