I can't think of the last relevant online advertisement I've seen. They're almost always out of context and uninteresting. On the other hand, magazine ads are usually well-fitted to the topics in the magazine, and I find I often read them.
The point is, I'm not really convinced that tracking is necessary in order to produce more relevant ads. I guess it's kinda necessary in order to track how many views an ad gets, but there's gotta be a better way to do that, and it doesn't need to collect any data other than "viewed++" or maybe a bit more to prevent gaming the system.
I haven't worked in online advertising for a long time now, but when I did it was in the early days of retargeting, and the startup I was at was pivoting to doing search retargeting. But honestly, without any real metrics to justify it -- I suspect just investor interest / industry buzz.
I ran some quick numbers myself to see how the early experiments with it were doing, in regards to click through rates, and I didn't see any statistically significant improvements. I became very very skeptical -- one of the many things that led to me having a large fallout with the founder.
Now I'm sure in the intervening decade there's been improvements, and this is just one anecdotal datapoint, so I can't make strong claims about the efficacy of retargeting generally -- but I remain skeptical.
Go into the market for a mildly big ticket item other than a house and do some searches or browse some websites with privacy blockers off. You'll get start getting "relevant" ads.
I went to a e-bike manufacturer's website a couple months ago and they chased me around the internet with ads for like a week.
For some ads, i think google, you can click/tap on that blue little X to close it. Then a clickable field appears, and when you click, or tap on you can choose "I already bought this" among the reasons for why you closed that ad.
Question is if one is willing to do that, or not.
I prefer blocking them.
I once googled airport tow tractors to see what their specs were. Saw ads of airport equipment for months after... I'm nowhere near buying a 16-ton tug to move airliners around.
I think the base cause of this is that we look for products based on life events; if the light burns out, we search for a new lightbulb. Google can't have this data (thank Dog), so can only serve targeted ads based on recent internet activity. Thinking of this in terms of PID loops, there's too much external interference, and too much lag in the loop for it to be really effective in calculating the next derivative.
The point is, I'm not really convinced that tracking is necessary in order to produce more relevant ads. I guess it's kinda necessary in order to track how many views an ad gets, but there's gotta be a better way to do that, and it doesn't need to collect any data other than "viewed++" or maybe a bit more to prevent gaming the system.