I don't really agree with this. I don't see the benefit in starting kids out with different equipment that they will likely eventually use. I did not start playing ball on different fields, with softer balls or tees to hit off of. I think children's arms can handle full weight discs just fine and will benefit from learning on them. With that said, usually less stable discs work better for the lower power and disc speed. Just my take.
I completely disagree. Heavy discs promote poor form as kids learn to use arm strength to get them up to speed, light discs make it a lot easier to learn good form. It's not hard to transition if they want to use heavy discs later on, and many people find that lighter discs work better anyway. I have a decent arm and I still throw most of my drivers in the 160s, my fiancee throws all 150 class drivers even though she can throw 300'. Just because you get better doesn't mean you have to use max weight discs, the lighter stuff is really useful especially for new players and even more especially for new young players.