There are buttons to unlock and lock your screen just as there are to recenter it when playing on free cam. Some people are just more used to having it default on locked and hitting a single button to unlock it to take a look around, instead of having it fly every which way when on free cam everytime you get close to the edge of the screen.
I mean yeah, getting used to free cam is overall the best option, but some people don't want to or sometimes even can't, there's a reason Riot originally adjusted it in the first place. Ignoring these people just cause you feel like being an elitist is simply rude.