That's a great question, tacticalogic!
Why do people want to compare apples and oranges?
Simply to say they are both "fruits" removes all distinctions between them, in advance.
This may simplify argument; but it does nothing to explicate the facts of reality (i.e., that apples are not oranges).
The great physicist Niels Bohr once remarked that "we are suspended in language," such that "we don't know what is 'up' or 'down'." I gather his point was that even science must acknowledge the perils and pitfalls of "mere" language, and do its "epistemic homework."
The knowledge we think we have of the world is nonsense, if it does not directly correspond to the actual facts of reality as observed by "objective" (e.g,. non-ideological) observers.
In short, he was referring science itself to the philosophical discipline of epistemology — the "science" of what do we humans know, how do we know it, and how do we know we know it. Plug in a little experience-based observation and logical reasoning there, and we must acknowledge that apples are not the same thing as oranges.... And thus ought not to be described in identical terms (i.e., because they're both "fruits").
I'm not sure these remarks help much in answering your question....
Thank you so much for writing, dear tacticalogic!
Because what they really want to talk about is oranges, and comparing apples to oranges is a way to turn a conversation about apples into a conversation about oranges?