All it's doing is recognizing "similar" patches of the image and coalescing them, which is what it's supposed to do, according to the standard. Yes, it's too aggressive.
The stated goal of JBIG2 is to recognize 'characters' on the fly and compress them together. It's not traditional OCR but I wouldn't take such a hard line.
It is essentially OCR where the alphabet is constructed on the fly from the document itself.
A major and highly pertinent difference is that if this OCR-ish procedure incorrectly classifies two identical letters as being different, accuracy is not affected, and the only consequence is a larger file. With normal OCR, seeing two As and saying they're different would be an error, but in this case, it's fine.
What this means is that, while regular OCR is inherently error-prone, this compression procedure can be fully tuned anywhere between no errors and nothing but errors, with file size being the tradeoff.
The ability to run this algorithm in a way that produces no errors may be enough to disqualify it as "OCR", depending on your point of view. In any case, it certainly changes things from "that's just how it is" to "this is a royal cock-up on Xerox's part".
Whether or not we're calling it OCR has zero bearing on the point of this comment. I can't believe this entire thread is hackers bikeshedding about whether it's OCR or not - it's like the definition of pedantism.