Wow... this was news to me. I have used it for years to help my family, purchasing 3 year subscriptions for each computer since 2007. I have pointed clients to Avast, with this being one of the (many) features that they loved, and gotten entire companies to purchase Avast because the AV is fantastic, but also because the Remote Assistance. And these weren't tiny companies. I went to use it on my new laptop to help someone and... I couldn't find it. Best part is that I moved everything to 12.1, so my other systems don't have it.
Look, I write software, too, so I know how it is adding and removing (and readding) features -- it's not an overnight thing, but this really complicated things for me, helping some users who I wasn't about to run through how to install other software (which they would then need to uninstall). It would be _nice_ if, in the future, if this came back.