> Is it rational or realistic to assume we don't have analogous perceptual and conceptual limitations
I never claimed we don't have perceptual and conceptual limitations. Indeed, recognizing that we do should make us extremely wary of "philosophical" concepts like "real" that appear to go beyond the obvious pragmatic definitions that I described, that are grounded in what we can actually do with things.
Pragmatism as a broad, basic, and reductive view of knowledge is self-refuting and incoherent. If "truth is what is useful" or "what works," you face a self-refutation problem. If you claim something is just "useful" rather than objectively true, then it has no authority. If it is claimed as objectively true, it contradicts the pragmatic premise that truth isn't a relation to reality. And what is "useful", anyhow? Is usefulness useful?
> Pragmatism as a broad, basic, and reductive view of knowledge
I have nowhere advocated any such thing. The fact that I used the word "pragmatic" does not mean I was adopting the view you describe here. Not everyone agrees with your philosophical jargon and the baggage it carries with it.
I never claimed we don't have perceptual and conceptual limitations. Indeed, recognizing that we do should make us extremely wary of "philosophical" concepts like "real" that appear to go beyond the obvious pragmatic definitions that I described, that are grounded in what we can actually do with things.