Also hyperbole, dotnet supported other platforms years ago via mono.

jsiepkes · on Sept 15, 2021

I think I would be generous if I stated 10% of the .net applications ran on Mono instead of MS CLR without source modifications. I even doubt more then 60% of the .net applications ran on .net Core (needed for other platforms then Windows) without modifications.

Meaning .net has nowhere near the "write once, run anywhere" support Java has.