Where I worked in the past they had a rule to only hire DBAs that could manage schema changes and such without downtime. Proper planning up front can mitigate the need to take a lot of those outages.

They still took a window a year for changes where there was no alternative. That is still seems preferable to me to the kinds of ongoing problems that distributed eventually consistent databases produce. You might have better availability numbers, but if customer service has to spend money to fix mistakes caused by data errors I don't know that is better for the business.