It's a huge debate about online vs offline. Every aspect has its own pros & con. It's just the matter of usage… The way we utilize, if they are exploited then definitely they are harmful. Online is a medium to make everything convenient for us, but that the sole reason for us being an addict to all the leisure of online. Offline is way better as keeps you busy in some sort of activity… Making your bodywork, which good for an individual. As said earlier "every aspect has its own pros & cons", even offline you overdo it then… It starts harming you by stressing you. Keep up the balance between the two & enjoy their pros.