So I think a demonstrative example of your claim would be if you knew someone who is as accomplished with regards to compilers, language design, tackling really hard long term projects, but not as good at self promotion, and elaborate on what the lack of that skill-set caused.

The only other person I know of who has started and lead to maturity multiple massive and infrastructural software projects is Fabrice Bellard. I've never ran into him self promoting (podcasts, HN, etc), and yet his projects are widely used and foundational.

It seems to me like the evidence points to "if you tackle really hard, long term, and foundational software projects successfully, people will use it, regardless of your ability to self promote."