Wat.
Fiends have lasers.
Great Khans have end game gear.
Brotherhood of Steel have end game gear.
There's a Marksman carbine free for the taking by the Boomers.
Orris, a guy that can be encountered in a quest at about level 9, has a hunting revolver.
It's not about them purposefully keeping weapons away from you, it's about no idiot in his right mind charging into Red Rock Canyon or Hidden Valley with guns blazing. People either avoid those areas or befriend the factions living there. If you can GET a kill on them with the Varmint Rifle you got from Sunny flippin' Smiles, then you're free to take their guns. You probably won't though, so you need to work your way up the power-ladder.
The only faction that uses cheap crap is the Legion. Everybody else and their mother will drop all sorts of weapons.