Can you get to level 50 in fifteen to twenty hours though?
My character is something like 130 - 150 in Fallout 4. I'm using several mods that make the game more of a high damage twitch shooter as well as greatly increase the toughness and lethality of Gunners and Raiders. It's basically a whole new game, and I usually have ten to twenty points banked because there's nothing left I need and I'm not wasting time maxing out states and buying perks I don't need. Really, the game has scaled with me since maybe 20 to 30. I can now dispense with power armor because enemies are (mostly) no longer bullet sponges, but I can also die very, very quickly, like two to three shots. I suppose one benefit of getting that high is getting new monsters, but honestly they are just tougher, more dangerous renamed versions of the same old threats.
Whether one's character is level one or level one hundred really doesn't matter, it's how the game is balanced for that level. Once one levels up so that large portions of the map are no longer off limits, level is larger irrelevant.