It's supported in all of the major engines. And you also can't rely on the garbage collector to run at a predictable time (or at all!), so the engine never calling finalizers is functionally the same as the garbage collector being unusual.

The only (other) visible effect of GC not running is memory exhaustion. WeakRef/FinalizationGroup not getting triggered can have lots of script-visible effects, so can be much much worse. I wouldn't describe that as "functionally the same".