It's not crazy talk, but it is, often really hard.

Any part of a process which has variable time or is at all out of your control is going to fuck it up.

Only if it's entirely unpredictable. Most of the things happening while most progress bars are, er, progressing (or not) are pretty predictable. I bet that at least 95% of bad progress bars could be improved considerably; whether it would be worth the trouble is of course a different question.