There's a fair amount of hyperbole in that statement. Most of the above products (Redis, Elasticsearch, MongoDB, etc.) don't have "thousands of individual contributors" and are developed primarily by employees of the backing companies.

Second, external contributors can use it in their work in any way that they want so long as it's not in offering Elasticsearch-as-a-service. They can even use for offering Elasticsearch-as-a-service so long as it's based on the current Apache2-licensed code rather than the SSPL-licensed code that will be in effect as of the next Elasticsearch release.

There are certainly valid criticisms of this decision, but a blanket statement that "thousands of individual contributors" are the losers here is an exaggeration.