I think you're substantially misremembering on the issue of things PCs couldn't get. As Pedantic points out, there are tons of monster abilities a PC can't get. What a lot of people complained about were NPCs with abilities a PC couldn't get.
As far as complaining about monster stats, there were complaints about monster abilities varying based on meta game concerns (minion status being probably the biggest complaint) rather than some in-world explanation. That's the "what can't be explained" argument I remember.