That seems like saying a steam shovel is bad because it moves dirt at scale. Machines do increase the reach of people, that is exactly what they are for.
Mass spamming is the very raison d'etre for social network companies. It goes by different names though - "sponsored content", "fanpages", "influencers", etc.
The spam did not disappear with people moving away from e-mail. On the contrary, it's just been given legitimacy by the platform owners - who all happen to make money from spam.