It's certainly not acceptable, I just think it hasn't been a priority for Apple since it's a relatively niche usecase.
It could also be a security/privacy decision to leave it broken but safe until they can implement camera access through WebViews securely.
The closest to any official reason I could find is a dev letting us know that mum's the word:
>I asked about this internally and the answer is that, right now, WebRTC is only supported in Safari. No WKWebView, not even SFSafariViewController.
https://forums.developer.apple.com/thread/88052#266901