Men have a pretty massive advantage over women in athletics. Hormones aren't as dramatic as the differences between men and women. The PC issue is what is preventing people from being real about this. This really isn't that complicated. It is just the politics around the issue that make it complex. People have issue with making women's sports exclusive, but they also don't want to ruin the competition.
Why don't we hear about FtMs dominating the competition or doing well at all? It is much more rare.
The only complication is that it is possible that if you give the proper hormones to a pre pubescent child they may develop more into their identified sex and/or gender than they would otherwise. That also raises concerns and various ethical questions in and of itself.
The issue and complexity has never been whether men have an advantage over women. Everyone knows that. If you're attempting to summarise the debate on that basis you're clubbing an imaginary seal.
The issue is:
How do we define sex in terms of athletics, and is doing so discriminatory
If it is discriminatory, is it still necessary, and do we have enough evidence* to support making a discriminatory rule?
Should women remain a protected class in sport? After all, we don't have a short person basketball league, and we don't consider the natural advantage of tall athletes to be discriminatory. So on what basis do we say being tall is fair, but having too much testosterone is unfair? Is it qualitative and/or quantitative
If you use testosterone as a proxy for how "female" someone is, where do you drop the pin? How much testosterone should someone have and for how long? Is it a good enough proxy to justify this?
Does someone who transition correct their advantages from androngenisation enough to merit fair competition?
What is considered fair competition in sport? Where do you draw the line between advantages that are fair and advantages that are not?
Is demanding otherwise healthy trans athletes to go on a hormone course in order to compete a medical ethics issue
how do you define Intersex athletes, who are neither transgender nor fit into any neat category, and who are sometimes unable to process testosterone at all even if they have a lot of it? These are not people who transition, they are people born this way who fit into no neat male/female divide, and yet are overrepresented in sport
* As you pointed out, there are no FTms dominating sport. So how do you make a scientific consensus on an issue where there is virtually no evidence? The rational may be somewhat sound in principal, but if you're talking about "this is obvious, no one can even debate it", and you're making that argument on an ethics and legal level, you need to do better than "men are stronger than women because testosterone".
Ultimately if you want to commit to discriminating against trans athletes (because even by the IAAFs ruling, this is fundamentally discriminatory, of course it is), you need to have really, really good evidence. And we simply don't.