Not really far-fetched. Look at Sinatra README for example: https://github.com/sinatra/sinatra

There are 11 versions of Sinatra’s README which don’t share any general templates. They should be manually edited after each release. This is kind of thing that needs automatization.

Plus, it is much easier to inject badges by a mixin, not by copypasting and manually changing some elements from your old READMEs.