I definitely get what you're saying here, but I think if I was given the choice between an internal reviewer that might glaze over some bad practices, or an external reviewer who will miss stuff like "oh be careful calling that code, there's gotcha X, Y, and Z that you need to think about", I'd take the former every time.
It’s usually possible to see if a certain piece of code allows gotchas or not. Global variables, implicit dependencies, undocumented apis or magic strings to give a few examples. If you have many such, then getting a reviewer calling out those bad practices is even more valuable. Even more valuable that they are external, because often many such smell-patterns are stuck due to some political stalemate or cargo-cult within the team.
Most gotchas are actually carried over from the open source framework you build on top of. Such knowledge is transferable and can’t hurt to get another pair of eyeballs to help you with them, assuming you haven’t spotted them yourself already.
