Holy crap, have you picked a bad comparison, if you're trying to refute my point.
Edit: To provide a bit more context: Mating dances in most bird species are not direct indicators of evolutionary fitness, but they are what is selected for. SCA events, Fursonas, and the like are the postmodern equivalent of mating dances. They are Conspicuous Consumption, Veblen-good displays of "I can spend my time doing this self-defining thing instead of productively". That's fine and dandy. I'm not judging people for making their mating dance some form of roleplay (because most any formal competition displays the same traits).
Edit responding to you edit: Okay, based on that thesis pretty much everything, beyond the bare essentials of life, is about sex. Which doesn't really sound plausible.
But very specifically: Furry conventions are about sex. The drunken orgy room parties are far better attended (And yes, I have seen hotel contracts that prove this) than the "main event". Nerd conventions are about sex. SCA events are about sex. They are not exclusively, but as social activities, one of their significant motivating factors is mate-shopping, and there is every indicator that the other advantages of social activity (collaboration and trust building, trading, etc) are not significant motivating factors. People don't get jobs from BDSM conventions (Actually, they do, and then those workplaces go under because hiring people because you're fucking them is dumb).
Perhaps more to your point, if these are mating dances, why do so many people who already have stable, long-term mates participate?