Just because doctrine itself is useless does not mean you cant outplay your opponent without it. If someone picks Partysans or Tank hunters and wins it's probably because they were better than opponent regardless of doctrine choice.
You'll go round-and-round all day with the theory crafters on this. If you try playing some actual games with Tank Hunters you will discover:
Even players with ranking of 1500 usually screen their tanks with infantry when they push.
Lots of them buy minesweepers.
Infantry of any type reveal PTRS cons easily.
Players can recognize the PTRS symbol. Even those 1500 rank players will kite the PTRS cons long enough to hit them with a shell or two, wipe 2-4 models, and force a retreat.
Tigers wipe PTRS cons easily.
PTRS cons have such terrible AI that they can't protect damaged tanks from Gren squads that are trying to finish off the tank. Players will literally walk right through the squad and not worry about it. Even PGrens with shreks wipe PTRS cons easily.
The 180 muni PTAB bombing run is slow, doesn't wipe anything, and does significantly less damage than the 200 muni general bombing run. (Sky insists that it is great and hasn't changed, and will use the lack of anything in the patch notes as "proof" that he's correct. Now go to Youtube and watch the videos of it wiping 3-4 squads or a Tiger and try to convince yourself that it's never been nerfed.)
The regular snare from cons has longer range and works better than the AT grenades. The AT grenades are mostly just usable in an ambush. Their range needs to go up.
I tried Tank Hunters in some 2v2's last night. It went much worse than when I tried it in some 4v4's as the players were better. I was able to ambush some light vehicles in the early part of games with PTRS cons. I nearly got a Sturmtiger, doing a lot of damage with the AT grenades but lost a SU85 and T34 trying to finish it. Once players lose a vehicle to an ambush it becomes almost impossible to make another ambush. That reduces Tank Hunters to a gimmick that's good only for about 10 minutes of a game. After that, everything in the doctrine is a downgrade from either Mechanized Support or Guard Rifle Combined.