Linux became as popular as it is because it could run on the most widespread desktop hardware: IBM PC compatibles. And that was possible because it was an open ecosystem.
Librem 5 and Pinephone both allow deep tinkering without privacy problems.
That is a disingenuous comparison though. Compare X86 market share when Linus started coding Linux and Librem/Pinephone market share today. The difference is that to have a snowball's chance in hell to grow and spread you need to be able to thinker and invent on the hardware most people use.
In the mobile world, Android allows tinkering, but also achieves much worse privacy and security guarantees