As an aside, I'm curious, to leucrotta - What part of 5e are you under the impression has monsters and PCs not playing by the same rules? They do play by the same rules, they're even built using the same rules and strictures, thee same progression, the same rules governing hit dice and proficiency bonus, etc., their abilities and saves are derived in the same way, their damage is derived in the same way... They absolutely play by the same rules as player characters do.
I am fine with 5th edition myself, but legendary resistances and actions are a pretty large deviation from playing by the same rules, where 3rd edition didn't have anything similar - I think one important point is that in the past there used to be creatures with special abilities, but in 5th edition it's standardized that bosses can do things player characters can't by getting an exception from the action economy.
Different topic, Pathfinder is mechanically very much 3.5, but it has so many custom classes and stuff on top of it that it can feel quite different at times.
