Tend to agree. Many individuals could write the libraries for ruby, python, JavaScript, and PHP. And it's likely that would cover 3/4 of your users needs. .net java and even some of the functional langs don't usually justify the dev time and experience gap.
* elaborate - small teams don't always have the experience or desire to support these langs. better left to the community
seems like it's mostly web apps that are building rest apis. Most web apps are ruby/python/php. I'm pretty sure, but could be wrong. My hypothesis is based on the builder of the web app uses langs they are familiar with when they build out a selection of client library. The claim of a lack of .Net libraries seems to justify my thinking
* elaborate - small teams don't always have the experience or desire to support these langs. better left to the community