i wouldn't say snobby, maybe biased, "miscommunicative", skewed, opinionated, or possibly just plain wrong? I agree with you in some ways, but many a psychologist would argue that more impact could be made in K thru 3 or so (assuming decent nutrition, parents, clothing, etc.). People's memories just may not allow them to remember how much impact his/her 1st grade teacher had on them. My mother raved about how awesome and impactful my 1st grade teacher was but all of I have is fuzzy memories about how nice a lady she was. My 10th grade geometry techer was awesome and I feel she was very important, but I could never say which one had more impact.
Allthough I do suspect a high school teacher may actually help less people in number (quality, not quantity) don't feel as though I am knocking HS teachers. To make a huge impact on someone's life in HS, a student may need special attention that only special types of teachers may be able to provide. Younger children are more mallable and plastic, while older kids are more set in their ways and many may be unreachable, and possibly could have been reached at an earlier date. Hopefully teachers like you will be able to get thru to the ones that are reachable, while many students who are already "there" need only guidance and support, an introduction to new ideas and possibilities? I guess what I am saying is at a earlier age, you may get more bang for your buck?
You can "really" make a difference at either grade, but maybe you can influence more people at younger ages, while you can really "turn someone around" at a later date, but not as many people for your effort.