If you scan headlines on something like HuffPo, you eventually find some kerfuffle about something someone tweeted, about a car accident, or sex, or race, or some other topic that usually takes more than 140 characters to express yourself about. People respond that they are hurt, or offended, or enraged. Apologies are tendered, careers disturbed or ruined, commentary follows.
Of course, it doesn't take an actual tweet. Lazar Greenfield had to resign from the presidency of The American College of Surgeons because of a joke about semen he made in an editorial.
Now, sometimes the tweet or statement is the issue, and sometimes it's just the excuse. It looks to me like people were gunning for Greenfield, as they were gunning for Larry Summers when he was president of Harvard. So what looks like "controversy" is really the public manifestation of a concealed power struggle. I'm just guessing about Greenfield, but that was clearly what happened to Summers.
But usually they are completely without reason or consequence. People like these things. They are like mini speculative bubbles. Everyone can get involved, generate comments, and read what everyone else thinks. The topic seems more and more important. The bubble swells up then pops in a matter of days. No one loses their retirement fund or their house, but it's a bit of the same thrill of simultaneously making a mistake with a whole lot of people you don't know.
I still think "controversial tweet" is dumb, but then, I rarely change stock positions and have owned a house for years without ever feeling the urge to pull any money out of it, so I'm scarcely representative.