That is exactly what the Silent Reds (not regular Reds) fix! Seems their marketing and my comment above isn't clear enough.
They have built-in dampening for the top of travel and for bottoming out. It's far more effective than o-rings and has a much better feel to it.
Honestly the biggest source of noise for basically all mechanical keys except buckling spring or cherry-blue style keys is the noise of the keycap or key stem hitting the bottom and subsequently the top of travel. Half of that is fixable with o-rings but that still leaves the noise at the top of travel which doesn't currently have any solutions as far as I know.