The easier it is to do something, the less thinking and decision making precedes an action. The ease and inpersonal nature of online communication and social interaction often results in people doing or saying things they don't mean or would never do otherwise. These things might feel great at first but might also result in regret and self distaste. With the missing control that restricted accessibility naturally provides, people have to implement personal stop measures to think before acting. An example typing a nastsy angry email or sms to someone and then instead of sending it immediately, save it into the draft. You'll realise you feel better and never actually send that mail or sms.