Furthering this argument, if a robocaller uses a phone number briefly and discards the number after it is banned, the next user attempting to make a legitimate emergency call using the banned number may not get through.
Excellent point - it seems that tightening up the ease of getting a new number would be important - yet that just causes other issues, people just don't want to have to jump through hoops.
But that is a good thing, since it will make an incentive to prevent robocalls, just like there is an incentive to not forward mails.