Stock typically comes with more preinstalled apps, does not scale, the comparison is also lacking since power users quickly can disable those background apps, that people often love to call bloatware. Again knowledge is everything as you can quickly tweaks aosp pretty easily and also get very solid OS.

You can also isolate apps with third-party apps that you even can get from F-Droid, island etc. there plenty… Once again you show knwoledge is key, not the OS.