>But since when did using a business's product come to require sharing (or not sharing) political views with the business's owner?

Since 18th century at the very least; see: anti-slavery sugar boycott[1].

That's if you absolutely ignore the parent's point that political views are things like specifics of policy, not whether some people should be considered subhuman.

>Seems to me that this is what has changed.

It seems so because you don't know history, and didn't do a one-minute Google search for history of successful boycotts.

The article I'm linking is in the "bite-sized" category.

Enjoy.

[1] https://www.bbc.co.uk/bitesize/guides/z3rj7ty/revision/7