Why is this tagged “Do Not Read”

No, there’s some troll who tags ‘Do Not Read’ for all new BL stories. It doesn’t have anything to do with the plot.

This is actually very wholesome and cute. Read it!

I see this tag on almost every manga. While I don't doubt there are people who use it as a troll, I personally think there are people who use it as a proper filter. The tag could be a way to avoid reading/rereading stories that may seem interesting but aren't really for them. I don't personally use it myself, but I can see a few cases it might be helpful. Maybe they saw a misleading cover photo(ie thinking it's Yaoi/Yuri but it's crossdressing/gender bend or vice versa) when the story wasn't what they were looking for. Maybe they read it before but hated the direction the author took the plot(ie horrible/unsatisfying ending or they introduce an annoying trope/character they hate). Maybe the story is picked up by a terrible scan/translation team and they find it impossible to overlook. Maybe they saw tags/mentions of tropes they hate and/or find controversial/uncomfortable that aren't always obvious in the title/cover/description(ie incest, rape, teacher/student, abuse, or big age gaps) because not everyone is willing to read certain tropes even if it's well written or the art style is nice. In these cases, it's not really used to tell others "DO NOT READ" but more as a reminder to themselves to "DO NOT READ" a manga they already that already decided is not for them.

Thank you everyone!! (=・ω・=)

Good point