On paper Guards are one of those units that are nice but in actuality are shit because they don't offer anything new that Soviets don't have access too already.
Penal Battalions come out sooner than Guards and thus will have veterancy compared to Vet 0 Guards. You can upgrade them and the AT Satchel is a good enough deterrent against dives that Vehicle Button is not needed.
What I am saying here is that the Soviet base kit is strong enough that it doesn't need Guards. It is not like USF and Pathfinders. Guards are not a bad unit but are worthless. Against a player with a brain, they are not going to let your Guards sit in prone for 30 seconds while they take you out. They will be hit with grenades, hit with mortar barrages, Stuka/Panzerwerfered or even air striked.
The lack of mobility make Guards an easy way to drain your MP when you can simply have other units that are cheaper and almost as effective.
This is why Airborne Guards are vastly superior. Not everything is about damage and 1v1 but more about how they fit into the army as whole. Airborne Guards are better due to the more mobile combat of COH2, and the Vet 1 air strike may not do alot of damage but it can force the enemy to move while your units are safely shooting at them.
Forcing movement is a very powerful tool when utilized correctly as a soft form of crowd control. Take for example a situation where you have a Maxim and it is getting flanked by an OKW blob. Normal Guards can't do much to help you accept touch the ground and await the anal pounding that is about to happen to your Maxims.
Meanwhile Airborne Guards with Vet 1 can force the enemy to move buying you time to reposition allowing you to hold the position or avoid a hard retreat back to base.
If your a Penal player, I would assume you would know at best you will have 1 Vet2 Penal at CP2, if all your units have seen equal action you might have all Vet1 Penals. The moment Guards hit the field and get DPs they are similar to or better than Penals at ranges 20 and above. At R20 Guards do 15.7 while Penals do 18.7, that is comparing 4 models to 6 because I am not sure if the PTRS damage figures are accurate if you include them Guards beat them at R20. And just so we are clear, Guards Vet1 is not being used for DPS calculation.
You also need to remember that Guards will Vet faster compared to AI Penals since they can reliably damage and chase away if not destroy LVs.
Next you want to upgrade Penals with PTRS, that now means you have 1 squad that is now useless in an AI battle. 3Penals/1Guard is going to beat out 2Penals/1PTRS Penal/1LMGAirborne thru sheer DPS along with Guards PTRS having way better performance due to the bug. Now you might want to include Airborne VeT1 ability into this, that pass takes about 3-4 secs to come in. Moving and resetting your units separately will negate it just as it would in you weak example of the OKW blob vs maxim. Literally breaking the blob into 2 smaller blobs would completely negate and force you to retreat just as it would with regular Guards.
Now the weird thing to your arguments is that you act as if Guards have to stay in fighting positions for their performance. They don't, they just perform better when they are. So PW/Stuka/nades/air strike/mortar will do the same to them as any other unit, also they can retreat while in fighting positions I am really not sure why you brought that up.