AE is NOT an audio app, Premiere is barely adequate for audio processing. PPro is getting a lot better but Audition is a well-integrated tool that you can use to process audio for film and deliver in any of the standard formats. Can you cut audio and make minor adjustments in AE, sure, but that is light years away from effectively processing audio and mixing it for delivery. Sure you can cut audio, do some minor editing, make some minor editing, and output to one of the video standard formats, but if you have problems you need to fix, AE is the wrong tool.
Scopes added to AE make it a lot easier to do the kind of color grading that you need to do in After Effects to create seamless composites but AE is a really lousy way to grade anything longer than a few seconds with more than a few cuts. PPro is just now getting up to the task of grading a film. Scopes are valuable to keep the pixels under control but AE is far from what anyone would consider being an efficient color grading tool.
The video editing tools in Photoshop are a nice feature for doing a very few specific tasks that can not yet be done in AE. I have used the tools several times in the last few weeks to do things that were cumbersome to do in AE.
Picking the right tool for the job depends entirely on the job. In my 25 years of using and teaching AE, I have run into more folks that are content to drive nails with a screwdriver than folks that pick the right tool, use the right app, for most jobs. If you want to make a decent living doing anything creative you had better learn which tools to use for which jobs or you'll be wasting a lot of time on forums taking most of your advice from enthusiasts with little more knowledge than you have.