That's a True Scotsman fallacy. I guess all those millions upon uncountable millions of lines of Java, Erlang, C#, etc code in production is not serious? Because it's running in a VM?
I believe that's why the poster referenced the "No True Scotsman" fallacy. It entirely depends on your definitions and you can keep endlessly narrowing your definitions. All of them GC, right? All of them are doing some form or another of incremental, right? (Some in all generations, others only in some generations, based on balancing and tuning needs.) Do all of them have realtime characteristics? Yes and no. None of them are allowed to stop the world, certainly, but does that mean that all of them or any of them can be called "realtime"? It's a semantic hedge forest.
