Is there a way to escalate that I'm not seeing? AFAI remember, all programming is done through status messages 11110000 and above.
Full Disclosure: I made a web synth and really want to be able to use midi to play with it.
To answer your question about why not to just limit the API: because that would be another data point to use to fingerprint users, and because the amount of engineering time that would have to go into Web MIDI support (including testing, security auditing, etc.) would never be worthwhile compared to putting those same developers on something that might be beneficial to vastly more users.
(Also note that Firefox made the same decision to implement nothing at all.)
The idea that "staggering few" is a negative disappoints, given it has almost always been the "staggering few" who've progressed humanity.
In my opinion, Apple has an incentive to keep the web crippled in some aspects, and this is just another symptom of that deeper underlying cause.
Well, I guess if I ever need WebMIDI features, I'll put a banner for Safari users to switch to Firefox.
(Or.. Maybe Firefox on iOS is forced to use the same engine as Safari..?)