Although they may differ in a lot of ways (of course they do, they're different events/sports), they're all alike in at least one major way: that they weren't conducted under the accepted rules and conditions that allow them to be considered for record-eligibility in their sport/event.
I don't disagree with the second sentence, although the first sentence uses some strange terminology. Breaking 2 was built maximally for time in a way that no marathon conducted within the rules of competition can be. I think that's what you mean by "watered UP." If so, I also agree with that.
Nobody would suggest that Bannister's sub-4 wasn't very significant in the history of the mile (depending on the definition of supremely used, you might get some argument, but that's neither here nor there--it's on the Mount Rushmore, and I happen to think that even if your definition of supremely means solely the top one, that Bannister's accomplishment meets that criteria, too).
I also wouldn't contest the claim that Kipchoge's Breaking 2 attempt was significant in the history of the marathon (although if we were to call it "supremely significant" and we're using the strict definition of "supremely" I would contest that).
But there are at least two things that make the above statements irrelevant to the argument at-hand:
1) In an early sub-4 attempt, Bannister had a pacer fall a lap behind to be able to begin to pace him later in the race; he ran just over 4 minutes and broke the British record in that attempt, but the governing body of British Athletics wouldn't sanction the record. Bannister himself later said that he was glad not to have broken 4 minutes under "such artificial conditions." That's the race that seems most analogous to Kipchoge's, both in that he didn't break the barrier and that it wasn't accepted for legitimate record-keeping purposes. So the race that you're comparing Kipchoge's to isn't the best comp, and the race that is the best comp wouldn't make your case.
2) Whether something is significant (supremely or otherwise) in the historical context of its event is largely unrelated to whether the person who has accomplished that significant thing should be ranked #1 on a list of performers for a specified time period. Those are different accolades that are judged by different criteria.
I agree wholeheartedly with the above. Kipchoge is the best marathoner we've ever seen to-date. But see #2 in the section above and replace "something is significant (supremely or otherwise) in the historical context of its event" with "someone is the best ever at their event."
I'm not sure whether I agree or disagree with the above statement (except the part about the editorial board of the website not deciding, which is obviously true, but also a red herring--they made a value judgment here, but it was also pretty much in line with a lot of mainstream thinking about what marathons are most import--the WMMs, WCs, and other major city marathons are all considered at or near the top of the heap, and that's what their rankings reflect) and I see how it's related to the argument, but I'm also not sure that even if it's true it supports your argument. If I accept your premise that athletes determine the importance of a marathon (which, again, I'm not sure I do), do I believe that because the best marathoner in the world (who was the only truly top marathoner offered a spot in Breaking 2) chose Breaking 2 over London any other legitimate spring marathon that that makes Breaking 2 the most important marathon of the year (over races like the other World Marathon Majors that were chosen by many of the top marathoners in the world)? I don't think it does.
In conclusion:
Mike Trout is the best baseball player in the world. He didn't win the 2017 American League Most Valuable Player because he didn't play enough games in 2017, but he is still the best baseball player in the world and is the player most likely to have the best season in 2018.
Kipchoge is the best marathoner in the world. He didn't top the 2017 LetsRun.com rankings because he didn't run enough official marathons in 2017, but he is still the best marathoner in the world and is the marathoner most likely to have the best marathon season in 2018.
The only way this isn't true is if you include Breaking 2, an exhibition conducted under unique circumstances outside of the accepted rules of competition, in Kipchoge's "games played" total for 2017 (or if you really, really overvalue his performance at Berlin).
It seems like a lot of you have a huge issue with the fact that LetsRun.com didn't count Kipchoge's performance in (the fun, exciting, and unique) Breaking 2 (exhibition). I don't have an issue with that. It wasn't an official competition, and if you're going to have rules about what counts and what doesn't when evaluating who was the best marathon competitor in 2017, that seems like the as good a dividing line as any to me (if not the best one).