Around 20 years ago I was working for a database company. During that time, I attended SIGMOD, which is the top conference for databases.

The keynote speaker for the conference Stonebraker, who started Postgres, among other things. He talked about the history of relational databases.

At that time, XML databases were all the rage -- now nobody remembers them. Stonebraker explained that there is nothing new in the hierarchical databases. There was a significant battle in SIGMOD, I think somewhere in the 1980s (I forget the exact time frame) between network databases and relational databases.

The relational databases won that battle, as they have won against each competing hierarchical database technology since.

The reason is that relational databases are based on relational algebra. This has very practical consequences, for example you can query the data more flexibly.

When you use JSON storage such as MongoDB, when you decide your root entities you are stuck with that decision. I see very often in practice that there will always come new requirements that you did not foresee that you then need to work around.

I don't care what other people use, however.

Every person I know who has ever used Cassandra in prod has cursed its name. Mongo lost data for close to a decade, and Microservices mostly are NOT used to solve real world problems but instead used either as an organizational or technical hammer for which everything is a nail. Hell there's entire books written how you should cut people off from each other so they can "naturally" write microservices and hyperscale your company!!