Read Bernays (or the Creel Report if you can find it) for an account of how personalised advertising and manual social graph exploitation worked about a century ago.
Of course, back then, they targeted with much less data. For comparisons from half a century ago to now, consider https://opendatacity.github.io/stasi-vs-nsa/english.html .
Never heard about the Creel Report before, but here it is: https://archive.org/details/completereportof00unit/page/8/mo... Thanks for the tip.