It's a matter of values and context. I think in general having a happy and inclusive community makes it more effective, and if I have to choose between the two

It's a matter of values and context. I think in general having a happy and inclusive community makes it more effective, and if I have to choose between the two I'll choose the happy and inclusive, if slightly less effective community. After all, who are we writing software for if not for people? There are of course some projects where the only effective option is one where jerks are allowed to keep others away- in that case I think that it should be seen as a bug in the community and something that someone should try to create a fix for, and not just something everyone is expected to live with.