I think that part of the problem is that an agreed etiquette for online behaviour has yet to evolve, or fully develop, - let alone be agreed upon and enforced - because the means of communication, as well as the systems and platforms that enable it, are all so new and have been developed so recently.
Etiquette, conduct and behaviour (online) lag some way behind developments in tech, as do sanctions for inappropriate (or rude, disrespectful and downright dangerous behaviour).
However,
@Macky-Mac is quite right, for there are undoubtedly some individuals who view the online world as having liberated them from all and any need to behave in a civilised and courteous manner to others.