Number format helpers - standalone?

Hey, just a question out of interest:

I recently created a sinatra project and used ruby-i18n in it. I
noticed that there are yaml files for date formats (and also numbers)
in the rails-i18n project.
They worked out of the box for dates.

So I wondered if there are number format helpers, and although the
formats are in the above mentioned files,
the helpers are in ActiveView:

So to use them with a standalone ruby project you have to extract it.
Is there a reason behind that? Wouldn’t it make sense to include this
in ruby-i18n or rails-i18n?

Just wondering about the reasons
Thanks,
Christoph