I setup my own geocities website in 1998, so they had to have had it then. According to the document here [1], AOL's web browser was introduced in 1995.
1998 is the later days of AOL. Its heyday was 1991-1995, when basically everybody got multiple AOL disks in the mail, you'd have TV advertisements telling you to visit a certain AOL keyword, and they were basically the only user-friendly way of getting online. (The competition like Prodigy or Compuserve had very clunky user interfaces, and GEnie and BBSes were text-only.)
The writing was on the wall for AOL as soon as Netscape and Yahoo came out in 1994.
Feels strange to say 1991 was the heyday. I don't know of a single person with a home PC in 1991, much less internet.
Mid-90s to very early 2000s was nonstop AOL commercials and CDs in the mail. Chat rooms were booming and you couldn't watch a single TV show without a "You've got mail!" reference.
"The future is here, it's just not evenly distributed." -- William Gibson.
I was the last of my friends in elementary school to get a computer - my first was a Mac LC in 1991. Where I was, they were rare in 1986 but ubiquitous by about 1989. Would go over to friends' houses to play Carmen Sandiego, Oregon Trail, or Number Munchers. I was on the WWW by 1994. Grew up in suburban Boston, so the area was relatively affluent and educated.
I suspect this is like how my 3-year-old (growing up in Silicon Valley) thinks that robots, self-driving cars, and drones are just an ordinary part of reality, while they remain science-fiction for many Americans.
Companies can be around for a while before they refine their product and really take off. I disagree with the idea that AOL's heyday was the early 90's. From my own experiences growing up - and even from just looking at their subscriber growth - their heyday (to me) is the late 90's. If you have a different perspective that's fine though.
The writing was on the wall for AOL as soon as Netscape and Yahoo came out in 1994.