I think I tend to prefer strict rules.The whole concept of strict level scaling is just stupid in my opinion. I assume it only exists because devs put rpg mechanics into games that aren't supposed to be rpgs.
I feel like strict level scaling is a terrible system. It undermines the whole leveling system. Some kind of hybrid system would make a lot more sense.
MGSV is like its antithesis. Enemies get stronger as you play, but they specifically react to how you play. For example if you do a lot of headshots then they'll make sure to wear helmets. Instead of level scaling canceling out player progress, it forces the player to switch up their tactics.
Also strict level scaling gets rid of the power fantasy. You can be a fully upgraded god by the end of the game yet you still have to watch out for starter enemies.