I don't follow, isn't this just how dota works? I'm not saying he's game breaking, just that I don't really see what his weaknesses are. Great abilities, tanky, high damage output. You contested that he only gets tanky when he's being fed, but unless I misunderstand the meaning of the word fed here he wasn't being fed in that game but was still one of the tankiest heroes.
I tried searching for your posts but I couldn't find them, but I'd like to read them. I'm incredibly new to the game so I'm probably wrong, but I'd like top at least know why.
Oh. For weaknesses:
-Poor early game contribution (290 base ms, 0.56 armor with 644 hp) He's easy to kill early.
-Horrible agility gain (the lowest in the game I think). So he'll have poor ehp if you don't get armor. Sure he can hit like a brick, but a very slow brick. He gets outcarried pretty easily if he falls behind.
-Really mana dependent. Ex: at level 6 he has 305 base mana. Devour costs 60, scorched earth costs 60/65/70 mana, and Doom will cost 150 mana. So unless you don't spam devour every 70/60/50/40 seconds for that extra gold you won't be at least 75% mana for teamfights. Just one teamfight would get doom and scorched earth cast will cost 210-220 mana. Thats 68% of his mana pool and I'm not even including the 110 mana for Lvl? Death.
You won't be able to regen that amount spent by the time doom is off cooldown unless you get arcanes, but then you'll lack the armor tranq would give you.
Thats the thing with Doom, you can be tanky and do lots of damage by buying str or carry items, but your mana pool will be crap and you'll hit extremely slowly. You can get attack speed and str items and again you'll have mana problems. You can go wizard doom (shiva's, aghs, refresher) but then your right-click will be lacking.
Thing with Doom is that hes great at taking out ONE hero (two with refresher) out of a fight which is only good if you need your abilities for mobility (puck, Anti-Mage, Qop), for sustained damage or when they are on a low cooldown (timbersaw, storm spirit). But he's crap against a team with multiple cores and who only need to burst once during a fight (ex: dp, Razor, sandking, Earthshaker, etc.)
You want to prevent him from balling out of control? Gank him, he really isn't strong early game and right-clicks really hurt him. Buy a linken's to block Doom or Lvl? Death if he's smart (which will give you a heads up to escape). Armor reduction destroys him and so do crits. From experience lycan is a pain. Try baiting the Doom on either illusions, other teammates, or yourself if you have aegis. If you're vulnerable to doom, don't initiate a teamfight and wait for him to use it on someone else.
Pipe of insight's active blocks the damage over time of Doom so teammates with it can save you. Unless he has aghs he won't be able to kill off any tanky hero such as bristleback, tusk or chaos knight.
Otherwise you need to rely on your team to keep you alive when Doomed. His greatest weakness is too much choice. If he needs to Doom 3 heroes on your team to win a teamfight then you'll probably win because your team will still be effective.