Boycotting isn't individual choice, however; boycotts, when they work, usually work due to PR and reputational effects rather than market effects.

Boycotting works through the stubborn minority rule [1]. Sometimes even less than 1% of the total population can enforce their rule for the whole country. This works as long as the rest of population finds the rule does not bother them match.

[1] http://fooledbyrandomness.com/minority.pdf

Wait, wait, wait.

I thought it was universally acknowledged that boycotts, generally, don't work, because you can almost never find and coordinate enough people that care.

The case of Kosher wine from the link shows how about 0.3% of population forced almost all wines in US to be Kosher by boycotting non-kosher wines. The important thing is that the minority should be distributed across the whole population uniformly.

A call to action on a public forum might not mean much on it's own, but it's still advertising the idea.