Sure do.

Substack the company was founded in 2017 [1]. At that point Substack the person was already a household name in open source — with 76.000 GitHub stars to his name his projects' popularity were on par with the likes of Mozilla [2].

Naming an upstart company after a household name that isn't protected by copyright is incredibly clever. You get to use an established and trusted name, but can't get sued for using it.

[1]: https://www.crunchbase.com/organization/substack#section-ove...

[2]: https://web.archive.org/web/20170115065014/http://git-awards... — GitHub stars aren't a perfect metric, but it's the best I can come up with to convey the degree of name recognition back in 2017

Anecdotally, I’ve never heard of this person until today (despite having heard of the company). I’d guess I’m not alone.