But scopes made with 8 bit ADCs do not have the same frontend noise requirements as 10 or 12 bit scopes - you can get rid of the noise uncorrelated to the trigger in averaging, but if your frontend is capable of giving you a similar LSB of noise, you get less of it in a single capture with a higher resolution converter. The 10 and 12 bit scopes that I'm familiar with on the market have lower noise frontends than their 8 bit counterparts, so you do get better uncorrelated noise performance in practice using a higher resolution scope than even an 8 bit scope with enough eres oversampling to match the number of bits of the higher resolution converters.
Averaging can still be useful on signals who's noise is not dominated by an 8 bit scope's frontend, yes, ok, but how many applications are seeing that? And moreover, how many of them rely on very fast averaging to try to reduce noise on the input signal in a particularly snappy manner? It's far more likely that the frontend noise or the quantization noise of the scope dominates the noise in the signal.
As I said before, the alternatives are not a catch-all for every application, but I didn't read the OP as explicitly needing a fast averaging mode without specifying a use case that needed it over other forms of noise reduction or increased resolution, so I suggested options that could yield similar or better results in most use cases that you could use averaging mode for as a stopgap or alternative. I stand by my recommendations because for the vast majority of situations, they will get you results in the same direction averaging mode can offer without having to worry about the waveform updates per second when averaging, which is typically (always?) unspecified. If the use case still requires averaging to see your tiny signal in the larger noise floor (why are you using a scope for this?), the things I mentioned can still be useful, but then maybe the (largely unmeasured) performance figure matters. And if you really are looking for that much averaging to see your signal of interest.... your effective integration time to see it starts increasing until it's actually over the processing time for a single screen update, so then you're limited by the integration time of the sampling instead of the update speed of the scope.