Well heavy inf still gets picked because you are dead meat if you take lighter inf. Cav one shots you, archers too, and if you get to fight heavy inf one hit will get you so low that any arrow will finish you.
Heavy inf gets nerfed over and over. Since the first beast we have had class limits in order to not play CS GO with 3 cavs running around. But still the devs keep pushing down the inf nerfs down our throats.
Sure, I get that the heavy inf meta is driven to some degree by the class restrictions, but at the same time if it was so weak we would expect to see the class restrictions maxed out more often e.g 2-2-2. But from my understanding, even on the most open map like Trading Outpost, this isn't the case, usually matches seem to be 1-2 cav and 1 archer max.
I certainly don't think inf are overpowered, although I agree with the throwing removal, but they are clearly filling in a niche use, and doing it well.