I think most people would say "Snake Oil" is more related to wires, cables, power cords, etc.
But separates like Integrated Amps, Pre-pros, and Amps are more about your personal preference in the hobby.
There's no right/wrong in absolute terms. Sure, it makes more sense to spend most of your money for the speakers/subs or at least equal amount of money for speakers/subs vs electronics.
But some people feel that their speakers already sound as good as it gets, so they now want to spend big money on electronics - even if the electronics cost a lot more than their current speakers.
Who's to argue that their current speakers don't sound as good to them as other speakers that cost $30,000?
This is a HOBBY. It's not just about enough power. It's also about getting what you desire and other intangibles.
Personally, I see no point of Integrated Amps, DACs, and some other things. But everyone is different.