system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the purpose of ISPs? Can we not have an internet without them?
gpt
Simplest explanation:  ISPs *are* the Internet.  The Internet is, quite literally, a network of networks (hence the name).  Each network is owned, operated, and maintained by an ISP.  When you sign up with an ISP, they are connecting you to their network, with the promise that you will have access to all the other networks connected to it.

In fact, smaller ISPs actually have to purchase access to those other networks from the larger ISPs that own them.  Some ISPs will have what's called a "peering agreement", where two ISPs will agree to connect to each other, with neither one charging the other.  However, only the top-of-the-top ISPs are able to connect entirely through peering agreements.  In fact, under this definition, both Comcast and Time Warner are "smaller" ISPs, because they still have to pay larger companies like AT&T for network connectivity.

You can't take out ISPs and still have the Internet.  Someone has to maintain, expand, and connect people to each sub-network, and that someone is by definition an ISP.  The only way to get rid of them would be to replace the entire Internet with some kind of distributed system that didn't require expensive cables or centralized servers.  It's theoretically possible, but there are a lot of technical challenges that still need to be solved, and it's unlikely such a system would match the speed and reliability of the current Internet.  Not to mention it would be *very* expensive to do so, and wouldn't have coverage in any area where people aren't adopting it.

A better solution would be to fix the political situation which allows American ISPs to have localized monopolies with little regulation.  It's fairly difficult to do given the current political climate and corruption, but it's much easier than building an entirely new distributed Internet that doesn't require maintenance or centralized equipment.