after ICQ, from what I remember AOL Messenger was the dominant force in the US, MSN was very popular in many countries, but across Asia, Middle East, and many Eastern European countries, Yahoo Messenger was the de facto standard.
Not dissimilar to the situation we have today with WhatsApp and WeChat and iMessage. Except back then you could use pidgin or trillian as multi protocol clients which solved the issue. Somehow, we have regressed so much in this area in the last 20 years.
The reason no one needs a multiprotocol client now is we all have instant, intuitive multiprotocol devices in our pocket at all times. That's what's changed in the last 20 years.
