One element is probably ageless. Professions that demand public performance attract ambitious, creative and often needy people who feel under intense psychic pressure and often take it out on people when the spotlight is not on (or they wrongly assume it is not on). There are even examples, or so I’ve heard, of this phenomenon afflicting people in the news media.

But an important factor is distinctly a product of this age: The cult of bad-ass, trash-talking that has come to politics, including or especially to political-media relations. This coincides with the ascent of formerly anonymous political operatives to quasi-celebrity status. Among both principals and advisers, the willingness to swagger and snarl and be combative with opponents and journalists is now often seen as a sign of strength. The trend is bipartisan. In the Obama years, many young operatives, who in some contexts seemed like decent folks, during working hours adapted F-bomb dropping personas in which being smug was cool and being combative was a sign of devotion to the boss.

You might say that Donald Trump, who expressed contempt toward anyone who challenged him, proved the case that likability doesn’t matter. Yet many who have spent time privately around Trump say that he was shaped by the hospitality industry and actually seems to work at being charming when necessary. Even if Trump is as unlikable as he seems, for most politicians he is not a useful example. It’s a bit like they used to say at Evel Knievel’s daredevil motorcycle stunts: Don’t try this at home, kids.