Homophobic behavior and statements isn't exclusively connected to what's taboo and what's not. I still have good close friends who are working hard not to say "Dude that's gay."
The gaming community also extends to the audience who, leaning on anonymity like a crutch, will use homophobic, transphobic, biphobic language like it ain't a thing to them.
Some people in the gaming community don't realize that there's oppressive language specifically coded for various identities in the LGBT community.
Now, it may be true that it isn't as bad, but western society still does has a long way to go before they're actually "cool" with the LGBT community.
On a surprisingly regular basis, I still argue with my family--who know I'm LGBT--about why it's socially regressive to limit LGBT protections to a state by state basis.
I'm still terrified as hell to admit I identify stronger with they/them pronouns than I do he/him.
That being said, the LGBT community isn't necessarily all bundled up and coddled among themselves. We still have to bicker with trans-exclusionary radical feminists (TERFS) and shit, too, so perhaps there's a point to be made that an LGBT-oriented gaming community is not indicative of safety.
Still, perhaps being upfront about being gay really isn't that big of a deal. Perhaps we shouldn't question why people make an effort to point it out.
There's still a lot of people who need to know they're not alone.
For those who don't identify with that feeling, there is still the Let's Play. There's still the thing they have in common with a whole lot of people who are scared as hell, even if it seems they don't need to be.