It's not for you and me, we just see a garbage "game", but holy shit is there a large demographic that loves what Roblox gives them.
Of course it's bad: it's factually and objectively bad, there's plenty of investigative journalism that unequivocally demonstrates it's absolute garbage and enables the worst kind of crimes the US can imagine. But, and this is important: that has nothing to do with whether it sucks or not. In fact, it "doesn't suck" enough for millions upon millions of people to use it every single day. Roblox is terrible BECAUSE it doesn't suck: the whole reason it's so bad for humanity is PRECISELY BECAUSE it's awesome enough for a large enough demographic to keep using it, while being opaque enough to the demographic that should be correcting this behaviour to not get it so that Roblox can keep getting away with it.
The absolutely biggest problem with Roblox is literally that it doesn't suck. If only it did, kids would stop playing it!
Roblox has, objectively, a terrible effect on the world. This is demonstrably true. It's not an opinion. But saying it sucks is. Words matter.