Some older laptops did have physical on/off switches for the wifi card (this was prior to the advent of a camera in every laptop). The old Dell D820 was one such laptop. That was likely not the only one.

Gradually they were dropped from newer models because the manufacturers saw no sales changes due to the presence/absence of the switches (i.e., not enough purchasers refused to buy the "new" laptop because it dropped the physical on/off switch, which is the only feedback the makers truly understand and pay attention towards).

And dropping the physical switch saved the manufacturer a small amount on each laptop, which when multiplied across the numbers built was either a nice profit increase or a small price reduction (or likely a little of both).