That's false. Similar thinking to how the MPAA said that downloading a MP3 is a lost sale. There was never a sale to begin with, the user is not interested in a purchase regardless of whether the pirated content is available.

Here, the user will just go through the checkout again in a browser without ab-block or disable it. Why would they suddenly not need a power washer because they're running ad-block?

In fact, if anything, it'll train the user to disable ad-block when they're ready to checkout--from _ANY_ site since most of them are broken under ad-block.