[bogomipz]

>"The internet is a decentralized collection of autonomous systems (AS) and the primary benefit of this setup isn’t exactly realized afaict, which is multiple paths via different carriers."

The primary benefit if fully-realized and is not about "is multiple paths via different carriers."

An AS is an administrative entity. Route prefixes belong to an AS. All routes with an AS have a common routing policy that is managed by a single entity. I can look up a prefix to find it's AS and then I can look up that AS's routing policies. Here is an example for Tier 1 ISP Spring:

https://www.sprint.net/policies/bgp

I could have single ISP that I buy transit from and I might have multiple links with them. If I want to understand how to take advantage of that for example with traffic engineering then I would look the policies for ISPs AS. I would then use those BGP community attributes on my BGP links to them in order to accomplish my own routing goals.