To date, studies show that over 60 percent of users access the internet from their mobile devices as compared to 2014, which was only at 40 percent. This means mobile users had rapidly increased over the years. If we observed Joomla's ecosystem, more and more developers have already updated their extensions to be mobile-friendly.
The problem when browsing the internet via mobile back in the day, there were simply too many elements being displayed on a small screen size. This somehow causes the browser to load unnecessary content which then leads to slow page load. So, in an attempt to make web pages load faster on mobile, Google came up with Google AMP.