Postgres etc are more complex than Redis, are they not?
Does your argument assume you already have a database, so you might as well use it for your cache mechanism?
Modern rdbms databases already have an in-memory cache. For 99% of projects there's no actual difference. The round trip will end up around 12-22 ms in all best possible cases.
Modern rdbms databases already have an in-memory cache. For 99% of projects there's no actual difference. The round trip will end up around 12-22 ms in all best possible cases.