speaking as the project lead for Matrix: I haven’t done a great job of balancing “build new stuff to show off how amazing Matrix can be” and “make current stuff super polished and amazing”. However, we’ve spent the last few years plugging away addressing that, and I’d like to think the situation has improved significantly.
Another consideration is that nobody yet has consciously gone out to build a Discord killer on top of Matrix. Element is currently focused on being a WhatsApp replacement for government users (as a way to bring in $ to make payroll), which often explains why folks expecting it to be a drop in replacement for Discord users have to readjust their expectations a bit. That said, Element could certainly end up competing proactively with Discord in the longer term.
Meanwhile, Matrix certainly suffers from being successful enough to engender very strong feelings from folks who are disappointed in it. Whether that amounts to being run badly is probably a matter of perspective.