I don't know about Fallout 3, but having played Fallout New Vegas a lot and beaten the game on very hard multiple times, i say that FNV is a complete joke difficulty wise. You can just level your gun to 40 and then one shot almost everything in the game with a rifle through sneak attack plus headshot, in old Fallouts (especially Fallout 2) not leveling combat skills would screw you over sometimes, combat skills just doesn't matter in FNV. Also in FNV you can freely open your inventory in combat to consume multiple stimpaks or multiple foods, making you a regenerating immortal god, where's in Fallout 1/2 you can't freely open your inventory in combat without consequences. Not to mention the infinite ways you can cheese the AI in FNV like climbing a rock when fighting non flying/armed enemies.
You don't need to git gud at FNV, the game is a joke. Say what you want about Fallout 1/2 RNG, but at least these games will always remain challenging, Fallout 2 on normal is a lot harder than FNV on very hard.