you can get away without it for hobby or educational projects.

If anything, the opposite is true.

A hobby project is much more likely to be made without a 4 layer board and may even be "flying leads".

When the professionall with his solid ground plane and careful layout still add decoupling across every chip, it is totally irresponsible to suggest that an amateur with a less than perfect board should skimp on something this important.

Forget about EMI for the amateur, who cares, but what about the supervisor that triggers because of a noise spike, what about "my processor sometimes stall, why"

Erik