To be fair, the differences here seem to be smaller than in other sports, suggesting that while testosterone is a factor it may be less than it is in other sports. If 90% of the competitors in these races are male, that would further impact this discrepancy.
Why would that matter? They're not running as a group; if you're the fastest then you win. This isn't a probabilistic thing. Lots of slow men crowding the starting line isn't going to impact who finishes first.
I'm not sure I even understand your argument. It's possible we're saying different things? What I'm saying is that if X people try a sport the records they set won't be nearly as good as if 100X people are trying it. Winners are by definition outliers, and the larger your population, the more (and more extreme) outliers you will see. So if there are five times fewer women than men () competing in a sport, that will impact comparisons between women and men, even at the top levels, at least if you want to compare innate ability. Almost certainly, the women's records and top female performances would look better if there were five times as many women trying the sport as there currently are. Do you disagree with that?
I pulled up the most recent Ironman race; there were 5 men for every woman in the competition. So I'm using that as a rule of the thumb. But the same logic applies to any population imbalance at the top of the funnel.
That's quite the leap of logic hiding in that deceptively small "all else equal", what leads you to believe that everyone in a race has an equal chance of winning it?
~~All the distances in those tables are significantly longer than the 50k this article was about.~~
Edit: Ah, I missed it due to the weird order - but my original point stands, there is no point in ignoring part of someone's comment when trying to rebut them.
Interestingly, the 100m record difference is about 10%, which is roughly the same as the gap in the ultramarathon records (and in the record mile time). So the difference is fairly consistent across distances.
I don't think it's quite that close -- there may be sample size/participation factors involved here. For example, the top US women seems to be competitive with the top ~10 US men, which in more testosterone-dominant sports would never happen.