While I agree with "how malleable opinions are...", the actual answer is, "not very malleable". Every well-designed study of political advertising I've ever seen has shown that it's impact is very small, in some cases unmeasurably small. Thus, for example, the 2016 Clinton campaign raised a lot more $$ than the Trump campaign, whereas the Sanders primary campaign out-fundraised the Clinton one.
Now, the impact on the politicians of fundraising, is not at all small. The primary advantage of personalized advertising and fundraising, is to help a campaign rake in more cash, which is both legalized bribery, and an incentive to stoke your base's outrate instead of reaching towards the middle.
The worst thing about the CA/Facebook scandal, is that it's become an excuse for a large swath of the Democratic party to decide that it didn't make any mistakes in 2016 worth mentioning (or correcting).
Now, the impact on the politicians of fundraising, is not at all small. The primary advantage of personalized advertising and fundraising, is to help a campaign rake in more cash, which is both legalized bribery, and an incentive to stoke your base's outrate instead of reaching towards the middle.
The worst thing about the CA/Facebook scandal, is that it's become an excuse for a large swath of the Democratic party to decide that it didn't make any mistakes in 2016 worth mentioning (or correcting).