Xamarin did an immense amount of work pushing that boulder up a hill. Glad you got results, but frankly it did a lot of damage to a lot of people. I say this as a Microsoft fanboy and someone who deployed sites you've heard of on Mono + Postgres + CentOS.
In the last year or two many .NET vendors went from "yes, it works on Mono!" to "it should work but no support." This indicates the formal death of the ecosystem to anyone but apologist hobbyists and thankfully we've gotten to a better place now.