Maybe after several months if they didn't belong to a raiding guild, but to say there was nothing to do at 60 in vanilla WoW is just false.
It took a long time to level to 60. I started playing on the launch day in Europe, and I think it was something like 17 days /played when I reached 60. Then there were the dungeons. It took weeks to actually finish them all, because they were hard. And most importantly, unlike the linear pipes of today, they were fun. I remember when my guild started raiding Molten Core about 3-4 months after launch, I thought that it was too soon, I wasn't done yet with the 5 mans.
Sure, vanilla WoW had its problems, but the first few months of it were the best MMO time I've ever had and I never was bored, not for a minute.