Good point. It's maybe hard to see when you yourself aren't very good at something. Even harder when you really like doing it.
Cloud providers are very proprietary and specific in nature, which is very off-putting to me personally. Putting some abstraction over it, like terraform, makes it much less specific. It seems less like "wasted niche knowledge".
I have never used MongoDB, just watched it fail spectactularly in other teams. I don't get it. If I know my data structures, relational is obviously the right choice. If not, I won't expect any meaningful document queries either. A simple key/value store should be good, whether that's in my RDMS or something like Redis.
Go is just a fresh Java, without all the cruft. Also dumbed down, which is a bit sad, but on the other hand very quick to move around in. I don't get how anybody can stand all the crazy tooling and configuration and setup around Java, Spring, etc.