And what do you mean, by "there is no competition."?
If no guys are around the perceived "main competition" to the love interest is eliminated. Just by the virtue that lesbians are much rarer than straight girls. Of course the amount of lesbians in yuri works is usually disproportionate to reality.
Naturally yuri revolves around lesbians first and foremost, so males do not pose any "threat" anyway, but as you can see many readers are rather paranoid and sensitive about that.
Well I like guys in yuri stories, They make the story feel real. Plus I like to see the guy lose. And, that one is as bad as it sounds. heteronormativity bores, and annoys me.
Well people are paranoid for a reason. there is just so much bad bait out there. And people will watch it in hopes of a good ending, because there is not many stories with lesbians to begin with. I used to do exactly that, but it's become too annoying for me.
I like me some genuinely good story with male (supporting & supportive) characters, too. Shame on the bad tropes.