> Airlines don’t collect most passenger information — travel agents do. Most passengers never deal with the airline until they check in for their flight at the airport. And standard travel agency procedures make them function, in practice, as quite effective “anonymizing proxies” for travellers.

So my takeaway is that for enhanced privacy I should try to book flights with travel agencies instead of directly with airlines. Is the advice still applicable or is it nowadays futile?

The tradeoff is you can't change anything if anything goes wrong.