>>96405462
You have to accrue 120 Power, and that's not taking into account blocking damage and things like lifegain. Now factor in that typically the most powerful creatures you can play at a decent curve have 4-6 power and most of the time they can't attack the same turn you play them. This means that in order to put pressure on players to actually present as a threat you have to either play high cost high damage creatures that are vulnerable to removal or you go wide with lots of smaller cheaper creatures that need a board state with artifacts and enchantments to buff them up and protect them because at any moment someone can play a wipe that totally erases turns worth of mana and cards in a moment - which means you will be going even slower because every protection spell and mana you hold up JUST IN CASE is one less creature you could be putting on the field to turn sideways. Thus, unless you build an extremely fast deck with some of the more powerful creature commanders like Baylin or Jetmir, you're committing to a slow grind that can be brought to a screeching halt at any moment if you Don't Just Have It to stop removal or stax pieces going up. And God help you if you run out of gas and get fucked for draw after removal.

Contrast even a high cost combo like Sanguine Bond+Exquisite Blood. You just sit in your corner building mana, maybe putting something or two on the board just to defend yourself, removing and countering threats as needed, then once you hit your needed mana all you need to do is play card X+card Y and if they stick - which is easy when all you have to worry about is protection - it's just GG.

Damage strategies rely on racing toward 120 (damage) spread among 3 people that can slow or reverse the number. Combo strategies rely on racing toward 4-5 (mana) and only removal can stop it. Combo is gay and boring but if your goal is to win games (which is the whole point of cEDH) playing any other deck is fucking retarded.