Like, I totally think that like, it can be like, waaay annoying the way a lot of people use 'like' like a lot. But, like, I actually do it myself, like, way more than I would want to admit. Like I'll catch myself inserting "like" where, like, no like is needed.
I don't think it's a sign of illiteracy (obviously since I'm guilty of it 😛) and while it annoys me it doesn't concern me, if anything it's a sign of language trends and speech disfluency due to lazy sentence structuring (using filler words) which becomes a bad habit hard to shake, especially once it has become socially acceptable. I do think it's useful as a discourse marker and would personally find it hard to try to limit my use of "like", even if I can feel that I ought to.