I am not a fan of this either, which certainly does not make it wrong, but the best way to convince yourself is to do an A/B of tracks while mastering (pre vs post). A friend sent me a track over the weekend complaining about two issues - his voice wasn't like another track he sent, and the master that had been done he didn't like. The difference in his voice was mostly gently reverb on the previous track, and the issue with the master was reverb on it. Without stems, I could only fix one of the two (the mix was actually very good from the same person that mastered it).
A visual to consider... if you think of a sonogram (frequency spectrum over time), reverb is essentially "smearing" that spectrum forward (imparting several renditions of the entire track on top of itself), so all the effort to avoid collisions in a mix can be undone with reverb on a master. The master he sent suffered from this, and it turned the bottom end into goo. Be very wary of what a plugin is doing and its limitations, i.e. if it processes everything the same way, on a master track it won't know vocal from guitar - it is simply "one size fits all" and does its thing.
Again, depending on the content and application, this is not guaranteed to destroy things, but definitely A/B the pre/post masters to convince yourself.