I can't find the link now, but something that really opened my eyes on terrifying PACs are was someone pointing out how they manipulate the political discourse without even spending a dime. They just sit there on a gigantic warchest and send out gangster-style missives like "hey it sure would be a shame if you supported X or Y and we had to drop $10M on pummeling you with primetime TV ads in the week before your reelection."

This kind of influence is completely untraceable through all the normal disclosure mechanisms since no money actually gets spent. And worse still, it offers enormous leverage— once you have that war chest, you can use it to issue hundreds of threats and only occasionally have to actually follow through.

It's just a completely different ballgame compared to a "normal" campaign finance option that directly spends donations.

not true. PACs cannot donate more than a pretty low limit to candidates.