I don't put a lot of stock into rules like this. Sometimes putting an effect on the master bus will will do something different than you will be able to do by processing each track separately. If there's an issue in the mix, sometimes the best thing to do is fine to root of it and fix it, sometimes the best thing to do is put a fix as the last thing in the chain.
I mean, I think we've all had experiences where the low end sounds too loud, but turning down the bass makes it sound too quiet. If that's the case, the clearly it's a different issue than level, or even EQ.
That was just a long way of saying "Do whatever works."
I'm not really interested in whether or not other engineers would approve of my workflow. I'm interested in whether or not my workflow creates good sounding mixes in a timely manner. If putting a multiband limiter on my master bus does that, then so be it.