It may have been "fine" to some people, but the doctrines werent all created by the same person, or balanced against eachother. Now they are.
Also, we cant make a 1 to 1 comparison between Armor and Blitz.
Armor is like all armor, blitz encompasses a plathroa of strategies and builds it would make sense that the emphasis of Blitz be on speed and support as much as hitting power.
Also, when most people look at the armor doctrines, they see a wall of text that says what looks like some bullshit buff.
"Pffft, HVAP gives all Allied tanks +33% pen"
When you compare this to the fact that HVAP, even when stacked on top of the upgun only makes the Sherman penetrate the front of a panther 40% of the time, the match up is still garbage, the sherman has no chance.
Yes, P4s will get mauled, but with the sherman upgun, a mere 60 munitions out of pocket, shermans are penatrating P4 front armor 102ish% of the time anyways, making the HVAP redundant.
All of these doctrine buffs, every last one of them can be explained by the math to make a perfectly legit and useful doctrine ability that conforms to the design set down by the devs at the start of the rework. \
So tym's right, its gonna be fine. Lets at least try it out. New stuff is fun.