he is saying not everyone has the time to even level another toon. Dont see how you are questioning this but ok.
his reasoning for there not being an achievement for 10+ max level chars was that not everyone has time to level alts. however, not everyone has time to do heroic raids or rated bgs/arena or collect pets or mounts, and yet there are still achievements for those, thus showing the error in his reasoning.
Grats. I will get there one day. I leveled monk to 90 first so that I could get the 1-85 stretch out of the way. All the rest are at 85 or better. I'm thinking I will take a year or more tho. I finished all classes to 85 in cataclysm only shortly before the MoP release.