GA today is much more than just pageview analytics. With something like Google Tag Manager, you can have non-technical staff add in event tracking for stuff like form completion or file downloads, without needing to get developers involved. Reporting for stakeholders is also robust because of its integration with Google Data Studio, Google Sheets and other related tools.
Ultimately though, GA wins because these organizations outsource web development and digital marketing work to agencies or contractors, and they are the ones that make the tooling decisions. GA is a known quantity, so even if their contract isn't renewed, a new agency will be able to take over the account fairly frictionlessly.
And there are more contractors that are GA-focused than there are for Matomo, and that's important when you're tasked with shopping around for agencies.
