I think this is a very priveleged take if we actually care about advocating for digital sovereignty.

In a perfect world, sure, build and manage a server with self hosted infrastructure. In reality people care about this stuff rarely actually have the money, time, skills or drive to manage a project like that confidently.

Its normal for people to want to allocate management of their services to a provider with trust to circumvent this.

For actualnconstructive advice to the people who can't do this: Try looking up to see if their are any nonprofit email hosting services in your country - they exist but usually don't do marketing and are often built on strong values. If not I really think using services like Tuta, proton, etc is leaps forward for your safety, privacy and ethics compared to Google, Microsoft, etc.