I'm really guessing here, but I suspect it is related to toe clips. As in, before "clipless" pedals, cyclists used toe clips and straps. And to get a better connection, cleats on shoes slipped over the edge of the pedal, and straps were used to trap the riders shoe in the toe clip and support pulling up and back.

So today's clipless pedals are missing the old toe clip - even though we clip our shoes in to the pedals.

--- Denise