There is again difference between blowing up a strategic dam and attacking a concert full of civilians.

First can have some actual strategic importance, cutting out energy, interrupting travel, et cetera.

It causes terror and civilian causalities, but that is again, a byproduct. If the latter is greater than the former it doesn't add to the revolutionary goal, I would argue it damages it and causes more harm than good for the group.

Second is pure terror, it serves no purpose for the group, vilianizes them to the public and makes the government they are fighting against stronger.

Any action that doesn't help with a revolutionary goal or even detracts from it, is useless.

Any action with no strategic importance and only creating terror is not only evil, but harms the group more then it helps.

There is a massive difference between terrorism and freedom fighting.

I am not saying freedom fighting groups don't do terrorism, we dont live in a perfect world. What I am saying that terrorism has no benefits and only harms not only the innocent but also the group commiting it.