Not to mention WoW and EQII came out nearly the same time and a key part of the marketing for both was how you had content that was completely solo where you could progress without the group-required design games like EverQuest had. So yeah, those games always had a solo avenue in mind. EQII had solo, group, and raid content. You hit a ceiling as a solo player where you had to segue into group content and then solo and group players hit a ceiling where they had to segue into raid content. Part of the reason I eventually left EQII was they started listening to the raid players who complained the solo and group content was too easy for them so they made it harder, putting it out of the reach of those who focused on that content. And they started putting in less and less for the solo questlines, so you hit that ceiling sooner because those who did raid content wanted more of it. I see similar arguments around these forums, and I've been grateful that the developers remain focused on their ideas of what this game is and what it isn't and work to have something for us all to enjoy.
