Pellets have fiber, but not "long stem" fiber that hay cubes and hay have. The long stem fiber helps them eat longer, they digest it slower, and it satisfies the horses desire to eat fiber. Without this long stem fiber, they will try to satisfy it by eating manure, wood, etc. Any barn that allows people to feed only pellets or provides
(basically) only pellets does not deserve to gave a boarding operation.
Pellets are basically a healthy type of grain, and, just like grain, should never be fed alone.
“Good things come to those who wait… greater things come to those who get off their ass and do anything to make it happen.” - Unknown