Because assuming that Penals are balanced, nobody is going to bother going with a risk/reward tier there is so many other options. Tier 1 needs access to some kind of anti tank, else Tier1 will just never be seen again.
Problem with T1 is that through the history of CoH2, it's been a crap or cheese tier. There's no such thing as "combined" arms. On T2 you might get a maxim, a mortar and a Zis. On T1 you just generally spam 1 of the 3 units.
-We spam clowncars till they nerf blitz, crew having 50% chance of dying, nerf damage on the move, cost, snipers inside, damage on the move for units inside, indirect nerf due to buff n changes to other units (222, Volks faust, SP cost)
-We double "spam" snipers till they remove sprints, overhauled OKW and add heavy counters to cloak/snipers.
-We got Penals to "cheese" heavy snow + satchel, steal OH weapons and finally their current iteration.
I think that in the end, PTRS can be fine on Penals. But i believe in a world, where T1 lacks direct AT (which nowadays can be get with cheaper T2) but compensates with good AI and utility (AT satchels should be kept).