For anyone with a computer, tablet or smartphone, social media platforms are merely an arm’s length away. They tempt everyone minute by minute, hour by hour to make a wisecrack, a joke or a “profound” comment to show the world how clever they are. Hardly a week goes by that some politician or celebrity is not apologising for, or explaining away, an errant tweet or post. This week’s winner — and the latest to succumb to the temptation to say something stupid — is Roseanne Barr and her racist tweet about Valerie Jarrett.

Within a single tweet, “Muslim brotherhood & planet of the apes had a baby=vj,” Barr managed to offend pretty much everyone. I’ve seen few shows cancelled this quick that didn’t star Tim Conway (a reference that shows my age).

“I apologise to Valerie Jarrett and to all Americans,” Barr said in a follow-up tweet. “I am truly sorry for making a bad joke about her politics and her looks. I should have known better. Forgive me — my joke was in bad taste.” But it was too late. Apology not accepted. Show cancelled. You’re outta here. Next?

To be clear, I found Barr’s tweet about Jarrett to be highly offensive. I don’t blame ABC for almost immediately cancelling her show, which pre-empted an exodus of advertisers.

Before cancellation though, the reboot of Roseanne took the political and entertainment worlds by storm with its astounding ratings and its take on President Donald Trump, which, if not pro-Trump, was notable for not being as hateful towards the President as most TV shows with a political angle.

Trump supporters celebrated its success, so now its star’s demise, taking her show with her, likely will be celebrated by the President’s critics. See? We told you so! Just another racist Trump supporter.

That will be unfortunate. I haven’t seen every episode of the new Roseanne, but the first couple were noteworthy for presenting a conversation about Trump that was respectful to both sides. Subsequent episodes I saw barely touched on Trump at all, and while viewership didn’t match the premiere, it remained strong enough to make the show “the highest-rated and most-watched series of the broadcast season”.

But Barr has also set back the opportunity to have a productive conversation based on the portrayal of a family divided on the question of Donald Trump in a way that reflects reality across so much of the country. Nothing else I’m aware of in entertainment television is addressing that reality in an honest way. The fact it was drawing millions of viewers each week positioned it to be one of only a few platforms in existence featuring a calm, rational examination of America in the age of Trump, apart from the flame-throwers who dominate so much of what passes for debate on the subject.

Barr no doubt feels sick for herself, her co-stars, her crew and everyone associated with her show. She should also hate that what she has done will result in a giant step backward for everyone hoping to get past the kneejerk accusations and indictments that pass for political discourse when discussing the president.

• Gary Abernathy, a contributing columnist for The Washington Post is publisher and editor of the (Hillsboro, Ohio) Times-Gazette