It originally started as just a fun side project.
But even if it hadn’t, are you suggesting we should no longer start big/community projects in C++?
Picking an unsafe language has the added benefit of distancing yourself from the toxic rust-or-die crowd, who can’t seem to mind their own damn business.
There are some cases where it’s just not possible to release the source code, even if you wanted to.
For example, if you’re developing a Nintendo switch game, you aren’t allowed to release any code that uses Nintendo’s sdk, so that means you also can’t use any copyleft libraries.
Maybe MPL-licensed libraries would be ok though. Idk, I’m not a lawyer.