Ruby is a general purpose scripting language that can be used for web development (rails, sinatra) but is often used for different purposes (puppet, chef, vagrant, shoes, ...).

And even if you'd assume web development as the only purpose, there's a lot of strings that are shorter than 23 characters: Header for request and responses, form fields passed by the client (usernames, passwords, ...), field names passed in hashes, table and column names, template and file names, URLs or even the occasional, totally rare string in a json structure. It's an optimization with major gain and little loss.