The question was, "what games popularized certain mechanics." The question was not, "what games created or introduced certain mechanics."
Yes, there were other MMOs before WoW, but WoW took MMOs to a completely new level of popularity. I didn't play ANY MMOs before WoW and wasn't really interested to, but it was so popular that I jumped on to see what the deal was. Since then I have played ESO, LOTRO, AOC, and one other whose name I forget.
Other MMOs were popular among gaming nerds before WoW, but WoW made MMOs popular to normal people.
I tried UO, AC, EQ1+2 and can say that WoW's beloved IP, look and feel, and relative lack of clunkiness in the controls and animations were big differentiators for me.
because it's flat out wrong. WoW aped most of its systems from Everquest, which most of WoW's development team was actively playing. They made some improvements on the genre, but the bones existed as early as 1997 with Ultima Online.
sure, we can quibble on the threshold of "popular" here. but you can't question that WOW caused an absolute explosion in MMOs after it. not like anything before.