Leon wrote:

"Wes Stewart" wrote in message
news

Why? If the cabinets have backs, and are screwed to the studs, why is
this less reliable than screwing a piece of plywood to the same studs?

Because the studs are only about 1/16" thick. The screw could easily be
pulled back out compared to being screwed in to 2 or 3" of wood.

What's the plywood attached to?