So why Private servers? Private servers will allow players to set up their own private matches further allowing them to choose and pick the players that end up getting it. Well games on public servers can result in bad game experience sometimes, due to the fact that you can face an unpleasant player sometimes. Those unpleasant players can be anything such as hackers, noobs or someone who has his mic always turned on.
With private servers you choose with whom you play with and in which region reducing the chance of running into people who ruin the gaming experience for you.