That’s a related, but separate thing .
Support for blueprintable components was added a while back (I don’t remember if it’s still considered experimental or not), but a component still needs to be marked as Blueprintable, and the vast majority are not. This means in practice the blueprintable components feature is useless to the people who really need it - those working in blueprint alone.
It’s a very easy fix, just add the Blueprintable specifier to all engine components that people might want to extend. Since it’s just a metadata change, there is no potential for bad side effects.
The request you linked has been around pretty much forever and is much harder to implement. It’s possible @Raildex_ may need both in order to achieve what he’s intending, but still making this particular easy change would be very helpful in itself.