A good pitch for dynamic (context) variables is that they're not globals, they're like implicit arguments passed to all functions within the scope.

Personally I've used the (ugly) Python contextvars for:

- SQS message ID in to allow extending message visibility in any place in the code

- scoped logging context in logstruct (structlog killer in development :D)

I no longer remember what I used Clojure dynvars for, probably something dumb.

That being said, I don't believe that "active" objects like DB connection/session/transaction are good candidates for a context var value. Programmers need to learn to push side effects up the stack instead. Flask-SQLAlchemy is not correct here.

Even Flask's request object being context-scoped is a bad thing since it is usually not a problem to do all the dispatching in the view.