When most of the games rules are about a thing that thing becomes the focal point. 5e also assumes pretty high amount of combat encounters per day to keep all classes in balance, if you are having less then it will make some classes just bad picks which can feel bad

Personally I don’t like it when people don’t play by the rules of the game we have decided to play together, so definitely things should work as the rules say and then ambiguous things are sorted with GMs world’s logic as “rulings”.

If you start by ignoring the rules and only consulting them when there is a dispute then I want to play another game with less rules to begin with