OST has medkits on all their mainline infantry that can be used on any squad but that doesn't change that it can also have one of the most inexpensive healing bunker. OKW light vehicles aren't any better than T-70, Stuart or M20.
This will be a shock for life for you, but Ost is not OKW and it does not follow exact same balance principles as OKW does.
Sturmpioneers medkits used to be unlocked with veterancy, and passive healing for volksgrenadiers used to be unlocked way before than vet 5 so whatever the original design was it doesn't really matter. USF was designed to not have a tier 0 mortar
USF lost the options that compensated for lack of that mortar.
OKW didn't lose anything, only timings were changed and accessibility was increased.
Claiming that it worked because Mechanized used to be meta ignores the fact that LVs are ALWAYS the meta for all factions, that the Battlegroup started seeing use because the flak ht was improved after being useless for a lot, as well as several key changes that OKW went through
Mechanized builds were nerfed, and so were Volksgrenadiers, which made Mechanized builds much less powerful. Ultimately there's no "meta" for OKW because the faction is competitively dead with 3 picks and 0% winrate in the last ML5, volksgreandiers late game bleed and inefficient trading being great part of it, which is only made worse by the lack of healing without backtech
The only faction in game that has a fully linear teching is Ostheer, because the mod team went out of their way to force a fully linear teching and disincentivize Tier 0 into Tier 2 builds, and still, OST can ignore the Tier 4 if not accessible. UKF has several side techs and Anvil + Hammer. No faction would be similar. Even OKW itself wouldn't change since its bad design basically always accounted for the player fully teching anyway, which works in resource inflated teamgames but gets absolutely stomped in 1vs1
May I present you UKF?
And Ost ALWAYS had linear tech, from day 1 of alpha.
It was NEVER meant to skip a tier, the fact it could in the past is a testament to bad balancing, which was mostly fixed now. Ost T4 was also made accessible easily, so that argument is out of the window as well.
It would still be a ridicolous munition sink. The only good med crate is the 221 because it can be dropped as single one to heal whenever you want field presence, which is a good tradeoff and a useful ability. Healing an entire match off sturmpios med crate *3 in your base costs simply too much and is far from what Relic probably originally designed med crates dropped by infantry for.
Spio med crates are not meant to be the only healing source.
Eventually self healing vet kicks in or you back tech, if you don't, that's on you, not on faction design, which screams at you to backtech to truck you've skipped regardless of path you took.