“Use Postgres for everything” is a great philosophy at low/medium scale to keep things simple, but there comes a scaling point where I want my SQL database doing as little possible.

It’s basically always the bottleneck/problem source in a lot of systems.

> I see people choose Kafka and SQS

SQS is dead simple, and if your in AWS (forever) it is "in the stack" with some easy to use features that may make sense to you (delay queue is a great one).

Kafka is... a lot. If you need what it provides, then it's great. You just have to be able to support it, and thats non trivial.

I can point to more than a hand full of Kafka project that exist because it was clear that someone wanted it on their resume. I dont think any one is doing that with SQS, it is just (a fairly good utility). However if you want to leave (or branch out from) AWS and you're reliant on it, good luck.