[dspillett]

> Legitimate interest is one of the lawful reasons for processing personal data.

Only if it is genuinely legitimate interest, in which case as you say they shouldn't even need to ask.

The reason they make them annoying to disable is the hope that people will stop bothering. In fact, they are usually hidden inside nested concertina UI elements so people don't even see the option to object. Dark pattern through and through.

The reason they ask even when only collecting/tracking strictly necessary data, is to try turn the public against the regulations by adding an unnecessary irritation. They want us to blame the legislators for causing us an inconvenience, when in fact the companies are doing so very deliberately because they are annoyed at the inconvenience they are caused by having to be transparent about the stalking that they do (or try to do).

> I assume this is just some trick abused by advertisers to work around GDPR

Sort of. And other similar regulations. Though it isn't actually GDPR-compliant by my reading, not by a long shot, the way most implement it.