I think it's about trademarks.
Take freebsd for example. They put tons of effort in the project for decades.

So of course they want to protect themselfes from copycats luring newbies into installing potential malware by using their name, logo and so on.

I don't like the idea of copyright, but I can understand the motivation behind this.

Openbsd on the other hand doesn't seem to care, no (tm) there iirc