One thing that some don't know:

Ever notice that vertical plate at the back of old school track and road pedals?




A slotted cleat is supposed to fit right on top of that plate.



That cleat was nailed or screwed to the bottom of shoes. This system prevented the forward or backward movement of the foot. The leather strap(s) prevented the vertical movement of the foot.

Toe clips and straps were designed to be cinched and un-cinched several times during a ride. Literally, every time you put your foot in you are supposed to cinch it tightly, then every time you stop, you reach down, open the quick-release and loosen the strap and take your foot out. Now you can see how clipless pedals were a significant improvement over this process.

The purpose of toe clip isn't to keep the foot from sliding forward. That's what the cleat does. It's purpose is to hold the leather straps open to allow the foot to enter them because once the leather straps are broken-in they become floppy and it's hard to get the foot in.