Asymmetrical balance.Like OKW don't have a stock HMG/sniper, USF don't have a stock sniper, Ost don't have stock light armors, Soviet don't have bunkers.
Asymmetrical balance means you don't have X feature within Y faction, but compensate for it with Z tool/unit/upgrade.
So lets break down your examples, shall we?
-OKW don't have a stock HMG/sniper
OKW also doesn't have fragile 1 model, expensive unit to protect from light armor rushes and they do have best AT upgrade on stock infantry, they still have the option to get the HMG through doctrine if player feels the need to, but the faction isn't dependent on it, so you have this option, moreover OKW is not really doctrine dependent, OKW doctrines open a lot of options though, specifically in elite infantry choices.
The compensations for OKW are quite obvious here.
-USF don't have a stock sniper
But they have some of the best stock infantry with now great scaling as well as variety of upgrades that can be mixed together for different situations, USF also have some of earliest and strongest light vehicles, combined use of mainline infantry and light vehicles makes up well for the loss of firepower that sniper would provide.
Again, compensated well for this shortcoming.
-Ost don't have stock light armors
Lets pretend for a while that 222 and 251 don't exist. Well, too bad they do. That is light armor, it have clear role and strengths, 222 can counter more expensive lights and is excellent scouting vehicle, if you lose it, you're not really on backfoot. 251 provides early on field reinforcement and can be upgraded with great area denial flamer weapons now. Ost does have light armor, it simply fills other roles and isn't designed to work independently, like light tanks.
Nothing to compensate here for, because the light armor is there.
-Soviet don't have bunkers.
Soviets have 2nd best mobility in game, the faction doesn't have or need bunkers, because it goes against its core design of aggressive play. You are supposed to force opponent into camping, not do it yourself.
So field presence capabilities(improved by ability to get faster M5 now with tech changes) makes up more then enough for lack of defensive structures.
Brits now on the other hand have no way of protecting the sniper using stock units at all or even score a kill on light armor, unless opponent overextends or you go side tech for expensive AEC, because PIATs are so shit. Being completely forced into single doctrine to be able to do so isn't really optimal.