I've heard the same about mvm.tf, but I found one person who said old.mvm.tf still works, so I've been using that for all my popfiles. I haven't encountered any problems so far. I'd still recommend learning basic popfile syntax so you can diagnose and fix problems yourself. You can learn about popfile writing from the links at the bottom of this post: https://tf2maps.net/posts/412536/
Or from a quick Google search.