If with lately you mean the last few expansions, even though it has been slowly getting worse for a long time (if not from the very beginning), you are right. Already in Legion, "randoms" were barely able to say Hi and Bye and many random groups were no fun. But every time I read "Don't play with randoms", I think this...
At the beginning of WoW, we were all randoms, but we played for fun and to play with other people and not just to run through dungeons as quickly as possible with minimal communication. We used to meet unknown people, doing elite quests or running dungeons together, having fun and then, when we or these unknown people, now called randoms, were doing dungeons runs down the line, we actually checked if the people we had fun with were online and whispered if they want to join another run, being in the same guild not required. Your name could even spread to other people you never played with, getting asked if you want to join dungeons or raids even without being in their guilds.
WoW's community, but also the whole gaming community has been going downhill for many years. Egoism has become worse even if it might only be a mirror of RL, nonetheless it made me stop having fun in WoW (besides game design decisions). WoW Classic Vanilla was the last time I really had fun while leveling with other people (some I knew from years ago, others I met for the first time) even if "endgame" and how many people played it drove me away after BWL. WoW Classic showed that we will never be able to go back from a community standpoint as many people I played and had the most fun with were people, that stopped playing many years ago and didn't stick after reaching "endgame". I don't think any of the many people I met and got to know better are still playing, with most having stopped around MoP and with some returning for a while for WoW Classic.