Totally. I am Italian, and seriously, most of the blog posts, tutorials and such written in my native language are so bad that only bad programmers can grow out of them.
Also, an open source project maintained in, say, Spanish is one I and others can't easily contribute to. That would be a disaster.
Projects would have to pick a language that makes sense, given their goals. Perhaps some would be keener on optimising mainly for the existing set of contributors?
I'm not sure about this, it would restrict the future changes, limiting innovations and putting the project at risk of dying when the developers leave, IMHO.
Also, an open source project maintained in, say, Spanish is one I and others can't easily contribute to. That would be a disaster.