I was always taught it doesn't matter the age of the kids, you always officiate your best, as this may be the most important thing in their life at the time - right or wrong.
So, if you don't want to ref the younger kids - don't. My choice is not. But I try not to knock those who do. That being said, I realize over the web that you are not going to be able to "prevent others" from saying what is on their minds. So, if you don't like it keep it to yourself - or accept what comes. Everyone is entitled to their opinion. (And the moderators sensor us every now and again - which is their prerogative).
Personally, I try to avoid the really young kids. Sometimes their games give me a headache and their is really little I can learn or practice - except maybe to help teach another young official.
So, what happens? Last week I was asked to do a G9/11 Rec game due to a shortage of refs. UGH! Usually, my worst nightmare. Well, joke was on me. Easy game to call. No controversies. No parents/coaches yelling. Hardly any running on the small court and I got to help a young official learn. All in all enjoyable and easy on the knees! I may try to pick up some more of these! Ok, probably not.