That view of compromise is actually at the core of what I don't see convincingly argued for.
Why shouldn't we compromise on principles, rather than just concretes, if it would produce pragmatically better outcomes? Why is it better to have dueling, inflexible idealized political positions, the hardline socialist against the hardline capitalist, each knowing they're right through some kind of metaphysical inspiration which can never be shaken by the presentation of actual facts? I would much rather have people in closer contact with reality, working out case-by-case situations pragmatically, than people living in an inflexible, idealized world where they know their views are pure and good, and opposing views are evil and bad.
The problem with using her novels as an argument for the position is that they only really work in an affective, sense, imo, as implying consequentialist arguments, sort of along the lines of a morality tale or fable: look what could happen if things are done this way, or alternately, if they were done that way. And I think a lot of people do read them that way; the famous "going Galt" plot, for example, is commonly taken as a parable for why bad things will happen if you institute too much regulation and burdening of productive individuals. But she explicitly disclaims "things will turn out better/worse" as a reason to accept or not accept her philosophical/political views, so her novels aren't supposed to be read that way. But they're actually more effective that way! Which is why I think it's so common for fans of Rand to ignore Objectivism and instead read her as more of a general pro-free-market, libertarian author.