This isn't about advertising - you can still advertise just fine, even more so on a search engine where the benefit of tracking is limited as the user explicitly tells you what they're searching for.
They were fined for tracking to detect ad fraud. Advertisers are paying per click, often quite a lot, and if you charge them for clicks that don't represent real humans they get grumpy and go advertise somewhere else.
For that matter, browser + ip fingerprinting can be server-tracked anyway, if less reliably overall. Especially with JS enabled. There are lots of tricks that can be used for this.
Aside, wonder how good/bad ip+agent fingerprinting could be combined with a url that feeds a small randomly generated string with a VERY long cache expiration, with server/proxy no-cache headers (e-tag per agent/ip). Effectively similar to a cookie, without technically being a cookie.
Not clear in this case, since while detecting ad fraud doesn't meet the "strictly necessary" requirements of ePrivacy (necessary for storing the cookie on your machine) it is still an open question whether the GDPR requires user consent for it. (Lawyers at advertising companies think that you don't, but that doesn't mean they're right)
Nice of them to spell out "we don't actually care about the users, get fucked" in such a clear and succinct way.