YY, Michelle and Edge.
And we can phrase it even more starkly:
Consider the difference between the phrases:
'Trans women are women'
and
'Men are women if they say so'
The first has a hypnotically recursive power, the second is an obvious absurdity.
It is in the end ALL down to language and the way it shapes perception. That's why the TRA lobby is so fanatical about enforcing their Newspeak. They understand that if others were to use plain language, the irrationality of what they are pushing for would immediately become apparent.
What is curious is that feminists don't seem to understand what the TRAs know implicitly. Most 'GC' feminists (including here) use 'trans women' or 'transwomen' unproblematically, seemingly without realising how profoundly they undermine their own arguments every time they do so. It is odd, this feminist supineness around handing the word 'woman' over to men, while at the same time trying to argue that men aren't women. Perhaps it is unthinking feminine deference to propriety, or perhaps it is more a conscious choice, with many feminists sincerely believing that people will be more open to their arguments if they demonstrate submissiveness to the 'correct' language norms.
In truth though, once you've linguistically moved men over to the woman category (via 'transwoman'), it's already over and done. Now the onus is on women to justify why we should be allowed to exclude this particular group of 'women'.
So on the question of how did we get to the insane place of sporting bodies letting men play women's rugby? It's easy: men renamed themselves 'transwomen', and thus it became morally impermissible to keep them out of anything reserved exclusively for women.