it's condescending, presumptuous and annoying. Unless you've checked someones profile and verified they're likely to be much younger it doesn't seem justified. If someones opinion differs from yours it doesn't make them younger, it means that they think differently from you. It's a tool for know-it-alls and it's getting on my nerves.
This may seem a bit redundant but w/e, it gets to me.
anyone else?