Veterans queuing via DF is what allows new players to clear those dungeons and trials in a reasonable time frame, though?

Unfortunately people like to prove why we can't have nice things. That said, I've also run into new/returning players that refuse to listen to my advice (my mentor tag isn't for show like most), or are outright disdainful; this toxicity runs both ways.

tl;dr it's not a design flaw. Just people not behaving around others.