Wow I've never heard anyone deny the very existence of cancel culture before. Or is this some kind of semantic distinction-without-a-difference?
Remember that something being a culture is about pervasiveness and normalization. It's not a mob harassing your employer because you posted photos with the wrong brand of political attire; it's it being culturally acceptable for a mob to harass your employer because you posted photos with the wrong brand of political attire.
Sure people protesting things is old, like you say. As are groups deciding to not associate with certain people.
But that is not in fact the same a nominally-impartial authorities encouraging protests for the purpose of having an excuse to impose a hecklers' veto on things they don't like.
And it is not the same as targeted harassment of anyone outside the ostracising group who doesn't bow to their demands.
And, and that's been true forever; in fact what is attributed to cancel culture is mild compared to what has been socially acceptable within living memory for displays of political wrongthink, what changed is that that comparatively mild social consequence became acceptable against the side which had previously only been the giver but not receiver of socially acceptable consequence for noncompliance with their norms.
By not being obtuse enough to conflate "this has happened at least once" with "this appears to be widely considered culturally acceptable".
"DEI" is not a movement, it is just a rebranding of Affirmative Action to emphasize the goals and break the association with (long explicitliy illegal, but often popularly associated with Affirmative Action) quota systems.