This doesn't really bother me. Philosophers' expertise is not in making specific moral judgements, but in making arguments and counterarguments. I think that is a useful skill that collectively gets us closer to the truth.

I skipped a few steps on the example. Think of it like this.

A: "States can do a lot of good'

B: "Well, maybe, but what do you think of drug laws"

A: "They're bad"

B: "What about the military-industrial complex"

A: "Bad"

B: "And you'd agree these are two examples of state power run amok in a structural way that's pretty pervasive across space and time"

A: "I guess so."

B: "So you agree that the state is fundamentally evil, tax is theft, and libertarianism is the answer, right?"

At this point, A will be thrown for a loop if they've never been subjected to these specific arguments before. A has been lead to the point where B is rhetorically strongest, and accepted premises in an unqualified form, which A might now wish to go back and qualify (but then A is arguing against him or her self).

This sounds like presenting an argument for a thing from shared premises - the most ordinary form of trying to convince someone.