And surely it would be better to have many implementations than a couple?

Its probably better to have more qualified people working on (analyzing and validating, particularly) a smaller number of production implementations than fewer people per implementation doing that with a larger number of production implementations.

Encryption is an area where doing one, very precisely defined, task correctly is critically important; the considerations in that domain are different than in many other domains of software.

No, I don't see how that's surely better.