Guards are a tough nut. They are expensive to start with, coming with slightly weaker AI in favor of slightly weak AT. They they buy an expensive AI upgrade that all but disables fire on the move. No they shouldn't be beating Obers, but should certainly give grens and volks a thrashing shouldn't they?
It not really a simple as that. There should simply be counter play to them.
For instance a specialized long range unit should be in disadvantage from specialized sort range unit at close range. Since axis are sort of weak at sort range units, Guards are hard to counter with infantry and can stand up to light tank when in heavy cover.
It was argued that Guards should be countered with mortars but since the latest nerfs to mortars that has become more difficult.
In addition their vet 1 ability is on of the strongest in the game not all providing unnecessarily more range but more DPS also.
Due to Guards performance Shock are not being used and now the plan do buff shocks instead of nerf Guards.
The original design of Guards being "jack of all trade master of none" was a far better design.