I think it's very likely that this is indeed what happened.
David Lewis who simply ignored the LP view about meaningfulness, and wrote books about [...] metaphysics
As far as I know, though, Lewis is revered for his contributions to logic and linguistics, but the rest isn't taken very seriously. What the hell is modal realism even supposed to mean? It may be, though, I'm in the wrong circles and there are some that do.
What the hell is modal realism even supposed to mean?
The claim that MWI is true and all those possible worlds really exist is pretty much modal realism, insofar as it's the claim that all possible worlds are as real as this one.
Very brief recap: The logical positivists said "All truths are experimentally testable". Their critics responded: "If that's true, how did you experimentally test it? And if it's not true, who cares?" Which is a fair criticism. Logical positivism pretty much collapsed as a philosophical position. But it seems to me that a very slight rephrasing might have saved it: "All _beliefs_ are experimentally testable". For if the critic makes the same adjustment, asking "Is that a belief, and if so -" you can interrupt him and say, "No, that's not a belief, that's a definition of what it means to say 'I believe X'."
A definition is not true or false, it is useful or not useful. Why is this definition useful? Because it allows us to distinguish between two classes of declarative statements; the ones that are actual beliefs, and the ones that have the grammatical form of beliefs but are empty of meaningful belief-content.
It seems to me, then, that both the positivists and their critics fell into the trap of confusing 'belief' and 'truth', and that carefully making this distinction might have saved positivism from considerable undeserved mockery.