As has been pointed out multiple times, no one claims that Oriental Adventures is racist in intent, but it is problematic (insensitive or racist) in effect.I don't agree. I think any critique of OA that doesn't take into account the influence Japanese media on Americans is faulty.
Japanese media has a huge influence on American culture, more so than other Asian cultures, and when Americans conflate all Asians as "the same", that stereotype is largely Japanese flavored. Your point explains WHY a pan-Asian D&D setting relies so heavily on Japanese tropes. In that sense, you are not wrong.
But it doesn't change the insensitive/racist effect of the book. It doesn't make it less offensive to those of Asian descent. It doesn't reduce the harm.