I like to consider Postgres the starting point for all of these things, that can be outgrown and replaced when appropriate. I do love just shoving everything in Postgres and seeing that I only end up needing a few additional dedicated services as the product groups. Redis is usually the next pickup for me.

Sure, thats a good way of working.. I just have the experience when handing over a project ( consulting ) anything i have put in place will never get replaced or kept for too long outgrowing its capacity by far, and offset with huge expenses in hardware or operations. Technically not my problem anymore ( except when it breaks on a maintenance contract ) but i still like to avoid it early if i can