And what makes you think you know the personal fears and weaknesses of every single voter, or that you can trivially flip votes by making ads about them? After all, in theory politicians are actually meant to implement manifestos, and if they are telling everyone different messages that'll get picked up immediately once people start debating the election down their local drinking hole.
The idea that you can buy elections through advertising is a typical position of the left (and these days, by extension, of journalists). Recall the huge fuss Obama and the Democrats kicked up when campaign spending limits were removed by the Supreme Court? Obama was even talking about a constitutional amendment. Then Hillary outspent Trump 2:1 on advertising and still lost. They disproved their own thesis.
The idea that you can buy elections through advertising is a typical position of the left (and these days, by extension, of journalists). Recall the huge fuss Obama and the Democrats kicked up when campaign spending limits were removed by the Supreme Court? Obama was even talking about a constitutional amendment. Then Hillary outspent Trump 2:1 on advertising and still lost. They disproved their own thesis.