I was nodding in agreement, but I realized there must be some catch here. If this was that simple it probably could've been implemented a while ago.
My guess is that there's some requirement that if it's a working number, it must be able to dial emergency services and that's the loophole that's being exploited. So the FCC's answer is if all numbers must work, push the check directly on the subscriber.
They make too much money from the spammers. Who wants to cut out such a large revenue stream?
In theory, yes. I would hope all the things that are "common sense" and "simple" would have already been implemented. However, as my professor of History from college loved to say "follow the money". If something could be simple and straightforward but is implemented in a convoluted way that is clearly suboptimal, someone somewhere makes more money as a result. It could be as transparent as Google Chrome implementing auto play with a "Media Engagement Index (MEI)", Apple being forced to implement USB-C on the iPhone kicking and screaming, or carriers and large call centers dragging their feet on doing STIR/SHAKEN correctly and passing along the billing information that I will remind you they already have because they like to get paid. So, while we hope common sense previals, at the end of the day, it only does so automatically when it makes business sense.
To your point about emergency services—while it's true that any unactivated phone must be allowed to dial 911, that rule only opens a one-way path to emergency dispatch. It doesn't give a device the ability to place outbound calls to everyday citizens. The real loophole isn't a public safety mandate; it's the wholesale VoIP market.