I've started a number of posts in this thread, but deleted them, because so often it's a story about some wanker on a train, or about someone who might be an opportunist, but if s/he were not, further publicising the case would constitute bullying.
However, here's a better pair of case-studies, with institutions involved, rather than individuals (apart from Jess de Wahls).
Douglas Murray has written in Unherd unherd.com/2021/06/the-hatred-behind-stop-funding-hate/ about the campaign group Stop Funding Hate, which announced its intention to get GB News advertisers to boycott the channel before GBN even launched.
As a contributor to right-of-centre news (Spectator, Telegraph, etc.), naturally Murray does have a personal interest, but we don't hear the case for plurality often enough, so this is how he makes it: by outlining a hypothetical approach against SFH: “pointing out that it is a hate-group — because it hates the free press, among much else.”
“We could... pretend that all Left-wing papers are a source of bigotry and that advertising in them constitutes an endorsement of it. As I say, you could do that. But it would be a fairly maniacal way to behave, and inimical to the idea of tolerance or respect for a differing range of views that must exist in a free society,” he writes.
As “a game that anyone with sufficient time and venom can play,” as he puts it, it's the sort of activism that escalates.
Meanwhile, in a Times article today www.thetimes.co.uk/article/jess-de-wahls-royal-academy-shop-ditches-work-by-artist-accused-of-transphobia-xdlzkf0l7 (about the Royal Academy agreeing to remove textile artist Jess de Wahls from its shop due to a few – apparently 8, complaints of “transphobia”), vengeful escalation turned up in the comments before too long, prompting one wry comment: “Fight cancel culture with cancel culture?”
How can companies and institutions prevent such escalations, such “purity spirals”, which hurt them as companies and hurt us as consumers, suppliers, employees, etc.? Since there's no way of being completely “pure” because rights are bound to come into conflict, how can we get on with our lives (coexisting with others) without having to have confrontations at every step?
What will it take? The commenter “Josephine March” in the Times comments references Arla Foods, which withstood a social media threat, but as someone else pointed out, smaller players (which I guess includes businesses or individuals) can lose everything in a social media-led attack.