Back in 2015 when I was leading a team working on a beta app for Android I noticed the more apps you install, especially the ones with push notifications, the more background processes were running when you check the system processes. This caused the phone to slow down a lot. That’s why I made this remark. I first wrote this article in November 2016.
Since then I believe Android has improved this problem. Certainly it’s a lot less of an issue on iOS, due to the different architecture and the fact that it was designed as a phone OS and not adapted from a PC OS like Android.
In any case I’m not a developer by training and more than honored to learn from your expert inputs. Please share.