[sophacles]

Define boycott gets:

noun 1. a punitive ban that forbids relations with certain groups, cooperation with a policy, or the handling of goods.

In the sense of "cooperation with a policy", this certainly is in fact a boycott. Also, a bit of a stretch, but blocking adds is forbidding relation with a certain group (advertisers).

Further, a boycott may or may not include suppliers (or any other group associated with target). For instance when some restaurant chain is being boycotted, you don't often hear "also don't buy $X apples, they sell things to the evil chain".

The point being - it is consumer activism, people are saying "I like your site, but I won't be involved in the unreadable mess that it becomes with ads popping up everywhere." That's a pretty strong message, and far more pointed than just avoiding a site. In the later case, the message is unclear... is the problem the site content itself? Is it the ads? Is it something else like the layout?