Not just lesbian.
Some devs plan their game for solo relationships including characters and are forcefully turned into harem.
Some devs plan their game for femdom without NTR including characters and are forcefully turned into maledom with NTR.
Lesbian scenes are "only" a popular topic and on the surface promises to get the game way more users.
The problem is that many fledgling devs "listen to the fans" to much and "follow the main stream to make more money!"
"Forcefully" really? ain't no one put a gun to their head... they chose to do so. It's their responsibility, thus also their fault.
Also... half those that "plan for solo relationships" have MC be with multiple/able to pursue multiple at the same time.
You can't go "O MC only ends up with one" if you allow the player to chase more than one... that's just retarded and harem bait.
And personally I haven't seen any games that genuinely do singular LIs go harem.
So unless the devs do it like "Katawa Shoujo", "Yosuga no Sora" etc. where it's individual routes you follow that locks you into that LI's path... then they shouldn't be solo LI endings only. (that'd just be shitty design).
... guess what most western devs go with. Harem until the ending. (just cause MC never does 2 LIs at once doesn't mean it ain't harem).
Dev's are responsible for the shit they get themselves into. Not anyone else's fault they lack integrity.