[OJFord]

Yes, uBlock can and does do more than DNS blocking.

Consider the simplest possible case: I run ojford.com and take money from Acme Inc in exchange for displaying their advert. They send me acme-banner.jpg, and I serve it at /static/current-ad.jpg with an <img id="banner-ad" src="/static/current-ad.jpg"> in my header or whatever.

A DNS block covering the ad would block my whole site. Effective, but useless. (Unless you actually intend to boycott anyone who advertises.)

uBlock however can block the #banner-ad element. (Whether community-curated or by you specifying it yourself.)

More realistically this might be say YouTube or googleusercontent subdomains that serve both ads and 'real' content.

[Melatonic]

Your site probably wouldn't get added to a block list though right ? For DNS based blocking I mean

[OJFord]

I'm not aware of a 'boycott sites that advertise' list, but possibly that exists – it wouldn't be added to a 'normal' ad blocking list though no, because they'd prioritise a functional site.

[pirates]

If the site is low volume then you’re probably right. But if I wanted to add the domain to my own list manually I couldn’t since it would break the site.