Alonso made a good point at Silverstone,
Harder compounds favor two teams, and softer compounds favor the other two in general.
So the problem here is that Pirelli is in charge of determining how hard or soft compounds to bring to a track and essentially have the ability to steer the championship because of this.
Not saying it´s a huge impact but rather a small sail gently tugging it in one direction if they so please.
Obviously Pirelli has it´s limitations of how hard or soft compound to bring to a given track like for example SS would probably not be ideal at Silverstone but with 4 different compounds there´s definitely some room there.
or it´s a bit late and i´m just rambling..