I don't understand your criticism.

People don't call themselves ultra leftist. They call other people that when they take positions that are in advance of what's currently possible as an effective action

For example, advocating for an armed insurrection in the US and gathering a dozen people to storm the Pentagon the next weekend would be ultra leftism.

So that advocate might be a communist, but theyre taking an action that won't advance the movement and will just get them and their comrades killed.

Ultra leftism is the flip side of tailism or right opportunism