What's wrong with account generation? Nothing. The problem is if they start sending spam to random people. So we can make registration or adding contacts paid (in cryptocurrency) and the problem is gone.
The majority of the user base would be gone, too.
I had a hard enough time convincing my friend group to use Signal as is. If they had to pay (especially if it had to be via cryptocurrency) none of them would have ever even considered it.
Most people would not, though, and that's the issue.
> What's wrong with account generation?
What's right with it? Accounts being generated (i.e. many inauthentic accounts controlled by few people) are always used to send spam, there are no exceptions. The perpetrators should be in prison.