I think the main problem with tanks is that the two most popular and effective classes are Assault and Support, both of which can simply solo a tank so long as they’re competent and patient, or easily take out tanks with a little squad or team work, especially at closer ranges.
Second the splash damage is weak, and this enables hide and peek spam, and a variety of other things.
Third the tank coaxial MGs have nearly 50% the velocity of their infantry counterparts. The MG34 on a Tiger has an initial velocity of 400 m/s whereas the infantry version has 740 m/s. They also have far shorter min damage drop off (28.75m for tanks). Were it not for the current net code issues and people having less time to react, these coaxial would be far less effective, especially at range.
Fourth the resupply depot system favours manoeuvrability, and therefore hinders the heavies, as does their greatly reduced ammo count! Only 18 rounds for the Tiger when it had an IRL capacity of 92, or 120 with extended racks! 24 with extended racks in game really isn’t great, especially considering it’s at the expense of a faster turret traverse!