system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why don't NFL teams train wide receivers to play cornerbacks?

For example the average cornerback is shorter and doesn't have good catching abilities. I would imagine having a receiver defend a receiver would be the best in 1v1 man situations.
gpt
There are different skill sets. Running backwards, zone defense, watching the qb, tackling, etc.

A receiver would be better at the catching the ball part (which is why sometimes they go stand in the end zone when someone is trying a hail mary, but not as good at the other parts.

Football positions, especially in the NFL are a lot more specialized than when we were playing in the street and everyone was a receiver and a cornerback.