Why do people love to siege mid?

lf you take the mid inhib then why not pressure another lane? Usually unless the top laner is a split pusher, the only lane that gets any attention mid/lategame is midlane, save for someone occasionally going top or bot to clear out a large wave. If you push mid then the enemy just has to defend like normal. If you push top or bot then they have to decide: clear out the minions pouring into their base or defend against the push. They won't just send a single support to clear out super minions so they will either be missing a damage dealer or a tank. In which case you can either force the tower or try to fight a 4v5. Either way it should have a favourable outcome. Is this wrong?