This is somewhat true. However, if you stop adding data to your profile it becomes stale. Since I deleted my facebook profile I moved cities, bought a house, a different car, and have new friends in real life. My old FB profile is probably still a good indicator of which way I'd vote in an election, but it's useless now for targeted advertising. The only way to make that break is to delete your profile now; slowly over time your real life will start to change and eventually won't resemble the digital you at all.
Data gathered from browsing websites that share data with FB (by third-party tracking or by direct acquisition of data from other companies, I'm not sure if FB does the latter) and from apps that include FB libraries (a surprisingly high number of apps) can still be associated with your ostensibly deleted profile.
