That's only good for small media like websites and images. Videos and downloads need to be cached in the provider networks, you simply cannot serve terrabits of data from a single origin. Well, you can, but networks don't like to operate like that. So ya, at scale, you need edges. The internet is dominated by companies at scale.
That's more of a CDN than edge compute. Edge compute would be something like having your Rails app run in a bunch of edge locations and then doing some eventually consistent magic to sync them up.
