Wrong. Oh, stealth definitely has its uses in this game, particularly if you're distant from your target, or have a Stealth Boy. But while it appears that the early enemies are scaled to match what you'd expect a low level character will have in the way of health, weapons, armor, and weapons skills, they are just as perceptive as the stuff you face in your late 20's. Primm is where you must face your first serious combats, and the escaped convicts were detecting my supposed "stealth" specialist halfway across the Bison Steve. I'd be edging down the back corridor opened by the maintenance key, and I'd get "caution" because some guy in the dining room (not the kitchen) could tell I was there. In fact, I couldn't really tell any difference in my "specialist" sneaker versus my much more combat-focused earlier run.
I was playing Very Hard + hardcoe, and later on I tried sneaking by some Vipers in metal armor I couldn't handle yet, and despite being very distant from just about everything, I had my choices between alerting the Vipers or the small radscorpions in the desert. Some sneak I was.
The upshot is I feel that there's no point in dumping points into Sneak until you're prepared to take it all the way to 100, and probably until level 12 when you can get Silent Running, which negates the sound issues from stealth entirely (not just the sound of running). The mid-levels of Sneak just don't help meaningfully. Working backward, assuming you're going to get 16 points from books and want to push for 100 Sneak + Silent Running at the first opportunity, there's little point in putting points into Sneak before about level 8 at the earliest. The only exception I can think of is getting it up to 50 so you can sneak a decent handgun into the casinos.