This era of computers slightly predates me so it’s difficult to understand the context - aol was a desktop application installed via cd that have you connection to other users and access to content somehow, but not via the internet?
AOL's brand name was huge, in no small part to their constant carpet-bombing of the entire country with CDs and diskettes promising to get you online today with 250 free hours or whatever. I really can't describe how impossible to avoid these things were in the 90s -- they were EVERYWHERE. So even after it became clear that the party was on the Internet and AOL became just a way to get to it, AOL still dominated the ISP business for a while. A number of things eventually did them in, not least of which was broadband.
It was almost bulletproof for the less than tech savvy.
For the audience it hasn't been matched wide since the iPad/iPhone
Imagine if AOL, the program, was your browser, chat, email, and internet connection all rolled into one single desktop program.
The clunkiness of an IDE, such as IntelliJ or Unreal Engine, that bakes a lot of things into one executable. The embedded browser in Visual Studio.
Dialup internet software makes a phone call to an ISP and handles the protocol for the connections all the applications on your machine use. AOL acted as a dialer itself so you could run lots of other non-AOL software, like Internet Explorer, Netscape, and video games. But AOL tried to be all of those things too inside their bloated app.
Some companies built private networks and services to these users before meshing with the internet at large.