I noticed this trend recently having studied hundreds if not thousands of patreons, webcomics, you name it, in preparation for launching our latest comic later this year (we've done previous comics in years past). It's been illuminating. I've accrued some data, and yes there is something to this whole BL thing...sorry, there just is. I say this having looked at thousands of different comics over the years.
My friend and I have been around the comic and convention scene a long long time. We have watched how comics evolved along with the internet from the 90's to now. One thing that has utterly flabbergasted us, and made us feel immensely disheartened, is the insane amount of money this newfound level of obsession with yaoi/boys love has become. You can also add in anything that remotely gives off a social justice vibe to that list too. I truly don't get it, not completely anyway.
I see people producing incredible, varied, beautiful work, leagues above this stuff, and they make pennies compared to these folks making BL comics and generating HUGE sums of money that my friend working at an insurance company doesn't even make and he's got one hell of a cushy high paid day job. It's. Insane.
I also found this a bit off putting "Setting a goal of making $50,000 a year doing a webcomic is probably not achievable either because only a tiny fraction of webcomics achieve Homestuck or One Punch popularity."
Quite a few people are now starting to make incomes in the $25,000 - $50,000 range. Wanna guess what genre is getting a lot of it? BL, SJW comics, and of course, Hentai/porn. (heck that's part of what drives BL too). NSFW stuff dominates patreon (but BL and LGBT stuff tend to do quite well even amongst that content).
It's already hard enough to sell original work, but clearly if you want to make money BL is the way to go. And considering some of us are actually trying to make a decent living at this, this stuff can be deeply depressing. I could, if I chose to, give you examples of objectively and technically beautiful art from a variety of comics, and then give you a list of comics that either take the SJW or BL angle and are often way less technically sound (though some are perfectly well done to be fair) and the difference is pretty stark. Just post your BL comics on tumblr and you have yourself an income it seems. Unreal.