Different teams have different abilities. You can't really make general rules around any of this. Should you use spanner as a default selection for your company's database needs? Maybe.
Some general rules make sense for common use cases. Like, I'll say that a relational DBMS is generally what you want rather than a graph one. For a single-node DB, I'll always use Postgres if I have the choice. For a webserver, can't really go wrong with NodeJS, though you might have reasons to use something else (e.g. cost to run).
But sharding is too use-case specific to prescribe something broadly like Spanner.
both good points, including the devs having different abilities and using a ready-made scalable solution. We're living in the world of having something working that you can test in a few days shrug
