I've actually seen the results of a database product being picked, the company behind which ceased to exist. It wasn't pretty, since at one point the product ceased to be supported and therefore neither any updates/fixes were made, it wasn't available in the repositories for new OS distros and eventually even the documentation for it went offline. Having to support a system that integrated with it was an unpleasant experience, all the way to it being eventually replaced with something else instead.
Therefore, it probably makes a lot of sense to base something as critical as your data storage layer on proven technologies that have demonstrated that they'll probably be supported in one form or another for the following years or even decades, unless you have a good reason for choosing something else.
Those reasons might deal with particular workloads or requirements, e.g. clustering solutions for PostgreSQL/MySQL/MariaDB/..., geospatial extensions, solutions to integrate with it through REST interfaces or even GraphQL or something like that, with a stable and proven piece of software still at the core of it all.
In case anyone is wondering, the product in question was Clusterpoint, about which you can read a bit more here: https://en.wikipedia.org/wiki/Clusterpoint a NoSQL database that actually predates MongoDB by a few years, as far as i know. Of course, now it seems like even their homepage is offline.