No polygon models used for animation would be my guess. The main reason I hate modern anime is the constant use of CGI. Badly constructed polygon models used for cars, backgrounds or worst of all, large groups or far away shots of people walking or fighting.
Crying over digital animation is really idiotic cause it's not a downgrade in any way, it's purely an upgrade, regardless of stylistic choices and trends you may or may not like. You could make anime to look like it was made in the 70s or 80s with digital tools easily.
Using crude polygon models that stick out like a sore thumb is a whole different thing that has nothing to do with digital. Hell, fucking Initial D had those horrible CGI cars despite being a 90s anime. It looked bad then and the technique hasn't improved much since.