Are they Telling you "you can't or shouldn't"

I was always puzzled as a kid when i was told "You Can't Do something" it was always more of a challenge for me to try when i heard that.

Often on this forum I hear people say "you cant" teach 8 yo rondos, build out, shape, focus for 5 minutes. Those are coaches i think you should be wary of, they have already put constraints on what is possible, perhaps they have even given up trying; or lack the skill to be an effective coach and instead place the blame of their shortcomings on their players.

Before people get upset, someone saying you shouldn't teach build out, and then having a logical explanation behind why it's not good to spend time on that in practice should be listened to and you should take the time to hear there reasoning and listen.

There is a big difference between saying shouldn't because it's not effective and can't because the kids are not capable of.