As Lenin said, "one must always strive to be as radical as reality itself." Radicalism itself isn't the point, and being radical beyond reality turns from progress into its opposite, reaction. Ineffective strategy hampers the movement, we need to have effective strategy and tactics, and we discover this through the unity of theory and practice, praxis. Peru's Shining Path is a famous example of confusing allies for enemies, alienating the masses and destroying the movement.

The origin of dogmatism can often be in failing to take an all-sided view of contradictions. Both the totality and the particularity of a contradiction must be viewed to avoid superficiality.

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