I agree, but I'd like to expand a bit.
It's not important to know a bunch of languages deeply. I think it's important to learn two or three languages fairly deeply and a few more at a shallower level.
One doesn't really know the right tool for the job until there's some experience with multiple tools. The more different the other languages are from you main language, the better one can judge the best tool. There are lots of different types of languages, and knowing a few types, their advantages, and their disadvantages can be really helpful.