The latest version is "supported only by" rails. (I mean that you should implement the server side part in your language/framework)
(in php/asp.net/python you should write something in backend for serve javascript responses as is it in rails with files .js.erb)
"When you follow a link, Turbolinks automatically fetches the page, swaps in its <body>, and merges its <head>, all without incurring the cost of a full page load."
Is the cost really that high to warrant this?
It prevents the browser from requesting all the external files (CSS and/or JS), so yes, it may be that high.