It's because authors have run out of ideas and rely on shock value atp. Who cares about plot and actually creating chemistry between the characters when you have shock value and people thinking you can forgive rapists?
Like come on. We had WONDERFUL BL manwhas who didn't rely on rape and shock value the whole time not even 10 years ago. We had Sign, BL Motel, The devil's temptation (the main couple. Fuck aleck.) and so on so forth.
Then came the era of stuff like Jinx, Even If You Don't Love Me and such and it all went downhill. There are still some gems out here, but they're hard to find.
(And for straight smut manwha, I swear it's only women who make decent ones.)

WHO THE HELL KEEPS GIVING THESE MOTHERFUCKERS ART SUPPLIES
90% of straight smut manwha with a male MC I swear it's just rape. rape everywhere, women treated as objects or just as holes, ugly bastards, and not a single nice MC in sight. The guy with short hair was right there. He was respectful. But we're given this trashy ass blackmail plot. Thank god I skipped all the chapters with that asshole and just scrolled really fast. If the last chapter is gangrape with those ugly mfs and the old guy. Istg. I won't be here to read it but I'm losing hope for decent straight smut manwha with male MCs. (Or any straight smut manwha made my a man in general. Cause if the MC is a woman it's always rape there anyway too so what's the point)