If you put it like that, the marker would only make sense in an otherwise serious conversation. But when it's used as a stop marker for every other message in a texting app, that's already a very casual and light-hearted environment, why do some people feel the need to reinforce it again and again? Maybe I'm overthinking it lol

I've indeed seen it used to mean basically 'this is serious but don't take it too seriously' if that makes sense, in the way that someone might say: 'university education is useless for the current job market lol'. I guess there are levels to this thing.