True but in the early 90s there was nothing else yet. But back then the whole internet was totally fringe of course.
Still, MIRC (as a client) was a common thing for all computer geeks until 2005-2010 or so in my circles. After that people started moving to whatsapp and the like. This includes people in the hacker/maker and game/lanparty community so very techy and niche but there it was still big back then.