> Also, I don't know how business stuff like this works, but if a company pays an ad agency for ad ideas, aren't they paying for ownership of those ideas? How many classic commercials were actually original ideas of the company whose product was being advertised? Yet we all still consider the polar bears to be a coca-cola commercial, WAZZUUUUUP to be budweiser commercials, etc.
To convert it to HN-speak, this is like forking an open-source software library, then branding it as your own internal original work. Then the kicker is the Twitter thread where he publicly insults the entire profession of the people they stole it from. So imagine that a company rips off an OSS library, then says something like "no OSS community would have created this."
It breaks an industry-standard norm in the relationship between ad/marketing agencies and client companies. Everyone knows that client companies pay ad agencies. But agencies make their livelihood on their reputation. So everyone who matters in the industry knows that Ken Stewart was behind the Coca-Cola polar bears campaign, or that it was Bill Backer behind the "I'd like to give the world a Coke" campaign. They've been inducted into the Madison Avenue Advertising Walk of Fame, which is literally something only ad people care about. Same with number of stars on GitHub.