I get where you're coming from. I think there are a lot of low-mid level players, including myself, certainly everyone I played against knew how to wavedash and L-cancel at the very least, but I only play Endless Friendlies and not ranked. A lot of people are new to the game, which is a good thing, so they need some time to improve before they become a threat to you at least.
I do get a lot of players who will start+quit if I take a quick first stock or the game isn't looking good for them, which I do kind of find annoying as we are just playing friendlies. Some won't talk at all (maybe they are full screen and only have 1 monitor). For the most part though I've found decent players. Only a few times someone will completely decimate me, and I try to play as many games as I can against those guys. Keep trying I suppose. I don't talk in the global chat, but I do talk in the match chat if my opponent is friendly.
I have heard people take ranked a little more seriously, so if you're on a good time you'll most likely find better players?