Why do I keep facing 5-mans?

I tried Smite out for awhile, and they had this system in place where you could only queue up as a 3 or less group or a 5 man group in order to separate the 5 man premades from the loners. Why doesn't League have the same system?

League's player base is much larger so long queue times aren't an issue. It would end the bullying 4 man premades do to solo players. It would make games more fair by ending the 5 man stomps on teams made of trio and duo queues.

The programming is already in place to make it more likely that a 5 man will face another 5 man, why not step it up and make it a 100% guarantee that will happen?