There are many people I run across who bypassed the whole Gmail and Google Workspace ecosystems and have rolled along merrily with me.com and other email providers.
It's not a given that users will have bothered to register for a Google account unless they grew up in the Bay Area after a certain time period.
Wind back the clock to when Google tried to roll out Hangouts and the Gmail penetration rate was even lower among the non-Android users out there.