You forgot, that its a Hobby-Cup.
Before the tire rules we had some Teamdriver who cam with 10 and more sets of tires..most noobs where scared about such a waste of money.
so for a begeinner friendly racing series its good to have tire rules. they dont have to aks themself what tires they have to buy..just buy a set at race day and its good..
on the Buggy or Truggy nationals u could use as much tires u want..as usual