Comment by sagarm

All of those are affected by analytics.

Ad slots will be filled whether or not you click. If you never click, you'll tend to match with either very low quality ads or ads that pay per impression (display ads).

Email registration is highly valuable for a business, so analytics won't be used to decide whether to show the modal but rather test different versions of it.

Cookies are too valuable to not push on users, because without them only the previously mentioned low quality ads can be shown. High quality and display ads match on interest or demographic labels.

The business decision to keep vertical videos is highly likely to be affected by analytics, and of course the choice of which videos to show is based on recommendation models trained on interaction logs.

The priority isn't making your experience better, though that is often an incidental result -- it's driving the business.