I wish FAANG paid government and defense industry salaries. Then our best and brightest might be engaged in something other than advertising and social engineering.
I always assumed Google and Facebook are just privatized components of total information awareness program.
So to answer your question, Google makes making spookie systems cool and profitable. Without them, the spookie systems would need to be built and deployed by 3 letter 'alphabet' type agencies and your local area geek may not be able to handle that much cognitive dissonance.