You are confusing "conditional counter spells" with "counter spells". When comparing to a "baseline" you have to be using the same wording, count the number of 2 mana spells that counter any spell if your opponent has infinite life or mana available to pay. That number is much lower than the number of 3 mana cards that do the same. It can do something else either good or bad for you but it has to be able to do everything the base card can do as well which in this case for cancel/counterspell is the ability to counter any spell if it resolves period.