Refreshable true damage is annoying, but for it to refresh darius has to get the kill, which overall will end up starving the rest of his team (especially the adc/apc of their team).
Plus he's easy to shut down early, he auto pushes whenever you trade with him, has no sustain, and he's extremely susceptible to ganks.
Sure he's good once he's in a fight, that's what he's designed for, he has no way to disengage though, which balances him out somewhat.
I guess the main problem on TT is that 3 champs are a lot easier to tank than 5 champs, but I don't think darius specifically benefits from this compared to other bruisers, darius just gets a tonne of hate in general.