Actually, dialup BBS systems existed well before AOL and offered chat-room capability. Content providers existed in the days of ARPANET but were only available to a very limited few users. As soon as the internet became available, USENET offered users thousands of topic threads in which they could make posts to share with other users. Email was started back in ARPANET days.
AOL just integrated content provision for browsers (http), email, and user posting chat rooms accessed via the same browser, but it was much more limited than USENET. Less confusing too, I suppose, but USENET and email were very simple to use. In fact, USENET and email servers all still respond to simple English text commands. All email and USENET client programs just provide a pretty graphical front-end but communicate with their servers using the text commands!