It's probably a problem they aren't in a hurry to solve because there's no reason to solve it. Any decently-funded small business can afford to use proper web hosting (Er, I love Digital Ocean. But they aren't really "web hosting").

Google (and basically every other reputable email host _and_ every "independent" email host) are blocking mail from services that host cheap compute power. A lot of Azure and GCP email traffic would likely be blocked, not just Digital Ocean.

If you want to start an email service, use something that isn't a known platform for spammers.