For me, personally, it's not because it triggers suicidal ideation - I agree with the research I've seen that suggests it's not a thing, or at least not a statistically significant thing.
For me, the issue is that people who say they're suicidal get attention and sympathy
For certain emotionally immature people, attention and sympathy is their #1 goal in life
In addition, teenagers want to both be cool and different, yet be accepted by everyone. You can't NOT accept a suicidal person, because what if they suicide themselves? If you say you're suicidal, suddenly everyone HAS to be nice to you.
All of this is to say that, no, all y'all dumb motherfuckers are not actually suicidal, you're just fucking sad, edgy, and boring, and you need to quit it because you're drowning out the actual struggling people.
Every damn day I see it "waaaaah I want to dieeeeeeee" no the fuck you don't, you're just trying to sound cool. Grow up.