Yep. Donations basically don't work is pretty near a universal opinion of anyone who has spent time looking at open source business models.

As beer money for someone's side project hobby? Sure, why not?

But to pay the full-time salary for someone even in a low cost country? Even $50,000 (per year) is actually a lot of money to collect through donations--in part, because as the author notes it's pretty hard for companies to just make a donation to someone.