You raise a good point. Availability is a huge advantage, especially for last-minute gift purchases. I haven't seen the good toys that I'm looking for on Amazon; I have seen them on Etsy.

On a tangential matter, I disagree with avoiding opportunities for teaching children delayed gratification in such a high impact way.

Think about it this way: every time you rightfully don't give your child something they want due to their bad behavior, you're giving them an effective lesson and improving their future life.

It's cruel to intentionally create situations that trigger a child; it should happen organically. It doesn't take long for children to adapt to understanding they won't get their way and start adopting appropriate self control.

Especially with modern research showing the damaging effects of corporal punishment, parents should take opportunities when they arise to discipline their children in a way that is meaningful to the child: withholding a toy they desire or another form of leverage.