Comment by SJMG

Nim is in part less popular because its BDFL, - isn't concerned with Nim becoming a mega popular language; it's enough that it has a successful user base to justify the effort/jobs developing it - believes that marketing is not required as people will choose Nim based off its superior features alone. (This is in large part true up-to people learning it exists, which is where marketing is valuable)

There are genuine shortcomings, of course. Every language has them.

It is something of a unicorn though. It's so pleasant to use at many levels of the stack from bare-metal to applications. People even use it for games.