It most likely shouldn't be normal in a company which is used for serious (as in, related to countries' relations or even wars in extreme cases) politics, no matter whether its founders wanted it or not.

It wouldn't be probably an exaggeration to say that ability to post a tweet in someone's name, or ability to see private DMs can have financial effects (scams, frauds of big proportions), or in extreme, yet not unthinkable, circumstances lead to loss of health or life (war, terrorism).