Then HSPA shouldn't be given on the computer.

Teenagers would find a way to cheat the system on the computer so I don't think that is an efficient way. Also, a malfunction could occur on the computer. At least on paper manually you cannot mess up the scores. Computers can sometimes go down, or input the wrong scores. For that reason I would prefer the traditional way of taking the HSPA. However, I am pretty sure about 5 years from now the HSPA will be on the computer since computers are taking over.