Recirculating bench bleeding went out of favor around 15-20 years ago. It's difficult to even find the little plastic tubes with the double thread fittings these days.
I just cut a short section of brake line and bent it back to the fill plug. Easy enough to do. I do recall the plastic plugs with my new master clyinder, but they weren't threaded, just push-in, and wouldn't do any real sealing.
