In 2016 the US was still vulnerable to a Kardashian style PR stunt attack. Trump performed this attack over and over again and garnered an estimated $2B of free advertising from it. Trump used Twitter to do this, but he could have used other social media. Trump's tweets were not newsworthy because Twitter routed them to millions of people but because large media firms wanted to monetize the hysteria created by the tw…
This hits the nail on the head. Late stage capitalism has completely fused media, news, and entertainment. This means that any person or organization who manages to "hack" the news cycle (i.e. finds a way to be in the spotlight on a very regular basis) can reap great profits. Like a presidency.
I don't agree that he could have used any other social media to the same effect. Information propagates and decays on Twitter much, much faster than on other mainstream platforms: if I post something, everyone who follows me sees it right away, and very few tweets are seen a few days after they have been posted. No other mainstream social network is like this. These properties have led to Twitter becoming the new AP stream for journalists, aka the entry point to the news cycle. If you want to dominate the news cycle, dominate Twitter - be it with racist tweets or asking for free chicken nuggets.
Twitter as a media apparatus has naturally played a great part in electing Trump. The Twitter leadership isn't composed of economists or political scientists or sociologists, so of course this kind of stuff lies completely outside of their concern (unless it brings good PR, like it does now). Same goes for Facebook, although the role it plays in the equation is different.