That's because Obsidian is black. But we're planning to add light mode in the near future :)
https://medium.com/@h_locke/why-dark-mode-causes-more-access...
Obsidian is a small team and I am pretty much the only person working on the website but I hope to add it soon.
(also applied to work with you!)
It's hard to know how many users they have, and they're overrepresented on this forum so it's easy to be carried away with our estimates, but let's say they have 1M active users. Then let's say 5% of them pay the $50/yr for sync. That's only $2.5M, divided between 5-10 people.
Good salary, but not outrageous and not much room to add many employees.