so unless a sufficient number of nodes total were comrpomised then tracking who is visiting where would be an effort in futility, no?

Yes, I was being hyperbolic, its probably unlikely enough nodes are compromised

The only notable case of a TOR user being tracked down that I can think of was a Silk Road user using his personal email address in malicious activity.

There was another one: https://blog.torproject.org/tor-is-still-safe/

But this was also technically a case of user error