I'm not sure I agree about the first example. Being unable to read a spell without any arcane (or divine) knowledge? That's a rule grounded in fiction, and can be explained thusly to the player.What happens if the player of a fighter or thief in D&D declares "I read the spell from the scroll we found!" or "I try and jump across the cavern!" where the cavern is wider in feet than the PC's STR score?
According at least to my reading of these boards, at most tables these action declarations default to failure, not for any reason to do with the established fiction but purely for reasons to do with the D&D (5e) game rules.
The second example just shows that the D&D 5e rules covering 'jumping' are bad. In 3e and 4e the maximum jumping distance depends on the outcome of your skill check. So, if I was playing 5e and decided not to house-rule this, I'd inform the player about the rule if he wanted to attempt something that the rules consider an auto-fail.
Having said all of this, I don't feel there's anything wrong with explaining the rules the moment they become relevant. In fact, when explaining complex board games, I'm doing the same thing. Otherwise it would be overwhelming.
Likewise, when using a setting that is unfamiliar to the players: Since their characters have been born and brought up in the game world, they'll know about a lot of things the players don't. Rather than providing a novella-size introduction to each player that they're expected to read and memorize, you only give them some basics and explain the intricacies of the game world as soon as they matter.