It's not like they keep getting "taller" all that time though, at 10/12 months most cats are as "tall" as they get (I once read somewhere that most cats are 90% grown at 6 months, but I can't find that again). It is hard for me to find the words to explain it, at first they just shoot up until they kinda look like a gangly teenager, and then they mature into a cat with more normal proportions.
Maybe pics will illustrate what I'm trying to say:
Flynn at 10 months old, 5 kilos:
Flynn 3 years old, 4.8 kilos, he has not grown, actually lost a bit of babyfat, but his fysiology has changed from teenage cat to adult cat, you can't see it in this pic but he got a lot broader in the chest too (his eyecolor also changed a fair bit);