Speaking as someone running a small business, and working with larger (200 employee) small businesses, this really isn’t the case.

Most places have Google Workspace now. It’s pervasive. Most also have Microsoft 365 in some form or another. People generally want GMail, not Exchange.

Syncing users between Zoom and Google is completely trivial as is automating onboarding and offboarding.

Paying 3 annual accounts is not much different than 1… and is a bonus if it leaves you the option to completely migrate off of on.

(Incidentally a pattern I’m seeing is a place has Google Workspace plus Zoom, and then employees buy their own copy of Microsoft 365.)