I think it's pretty reductive to boil down linux' success to the choice of license. There's governance model, development model, institutional inerta, ... - and the linux ecosystem contains tons of permissively licensed pieces of software, some of which massively contributed to its success (the once-default webserver that came with its own permissive license, the APL). Even the kernel includes APL, BSD-2 Clause and MPL'ed code.

To the contrary, GNU Hurd is GPL'ed and is much less successful than the linux kernel.