I was "corrected" in the thumb method at our academy back in '81, and subsequently reinforced by Farnham, Ayoob & others. We taught it at our department after that till the end of revolvers in '88 with the issuance of the Glocks.

The thumb method is too vulnerable to leaving one or two empties still hanging on, and if that happens it's irrelevant how fast the rest of your reloading technique is, since you'll be adding time in getting your cylinder cleared.
The reasoning I was given was that you do not want to risk catching a rim under the extractor star at worst, or even having to shake, rattle & roll to get a partially extracted case to drop clear.
It's hard to jam a revolver (with good ammunition) in general, but one jam that can get you killed is a case under the star. Can't clear that one in a hurry with a Tap-Rack- Bang.
Over the years, I've had cases do both when just fooling around on my own time & using the thumb method in laziness.
Punching that rod, assuming you have adequate clearance with your grips, makes for a very positive full ejection.
Casual shooting offers no immediate risk beyond the nuisance of digging a case out from under the star, but as pointed out- under stress you'll revert to what you're used to doing, and I still carry a DA revolver now & then for serious purposes. I try to stay consistent in how I dump empties.
If range stuff is all you'll ever do with the DA revolver, doesn't matter as much.
Denis