Why has this not been brought up years ago?
~~There has never, to my knowledge, been any reason for someone to buy more than one set of boots. ~~ I have been corrected. There is so little reason for buying multiple boots that we might as well remove the option to do so.
The recent rework to
proves that it is possible to restrict a champion from purchasing ANY boots.
So, why are we not restricted from purchasing more than one set?
I suppose it could be possible for multiple boots to somehow benefit some champion(s) in the future. Maybe quadra-peds will be able to buy two sets.
Further thought about this concept made me decide that this would not be a good idea. The relative cost of boots compared to other items, and the necessary amount of free stats that would be needed to make up for the difference in stats in order to make a champion have any sort of balance would be completely broken.
Maybe their effects will change in a way that will allow for their effects to stack for everyone. still something that could potentially happen in some balanced way, ... I suppose
But for now, the only reason for anyone to have multiple boots is because they simply don't know that they don't stack do not stack all of their stats, and those that do are not effective, or they're trolling.
If they simply could not buy more than one set, they would learn very quickly, and not be able to troll in this way.

or 
but i have 6 feet...