From all I've heard, making a profit isn't overridden by the individual's interest not to be tracked - otherwise, Google Ads wouldn't exist in Europe, at all, and Remarketing especially not.
It's not unnecessary data - FB needs that data to target users with ads, the shop needs FB to show ads to people that are likely to buy what they've been shown. I do agree with you that this would be very different if there was no business interest in tracking users, but there is.
As far as I know, remarketing hasn't yet been shown to be valid at all under GDPR. Someone probably needs to make a test complaint. There may already be one in the works. It's but a detail within the general case of Google or FB advertising in general.
Google Ads have already been fined €44m under GDPR, and I believe there is another case already in the French system.
Showing ads is not the service provided as no one at all would accept them optionally. FB, and Google, should be targeting in non-personal ways even where that necessitates less targeting. That was part of the point on which Google got their €44m fine.
As seen in TFA, the web of third party tracking appears more liable, and in need of consent than many, particularly American companies with a vested interest, have claimed whilst hiding behind those.
It's not unnecessary data - FB needs that data to target users with ads, the shop needs FB to show ads to people that are likely to buy what they've been shown. I do agree with you that this would be very different if there was no business interest in tracking users, but there is.