I've seen a lot of people use AssistiveTouch as a replacement for the home button too. It's definitely because they want to reduce wear on the home button and is also an easily copied habit from one person to another.
I'm also guessing that the amount of dust in certain geographies may play a bigger part in the home buttons not working well after sometime, since there is a gap for dust to get in in all the iPhone models (AFAIK) till the iPhone 6s series. The iPhone 7 series is the first one to eliminate the press button and replace it with a haptic one, which helps in water resistance and also eliminates dust getting in at that point.
I'm also guessing that the amount of dust in certain geographies may play a bigger part in the home buttons not working well after sometime, since there is a gap for dust to get in in all the iPhone models (AFAIK) till the iPhone 6s series. The iPhone 7 series is the first one to eliminate the press button and replace it with a haptic one, which helps in water resistance and also eliminates dust getting in at that point.