I am not a fan of manifestation/law of attraction for among other reasons, the blaming that you describe as ruminations and from what I read from others are often not personal ruminations but attacks from others. I discuss this in my https://medium.com/my-unpopular-opinion/vision-boards-are-bull-sh-t-9789be8f2f8a subtitled "And a perversion of the law of attraction." The latter I have railed against for the victim shaming/blaming aspects of the "law" as stated by new age spiritualists but I recently came up with a definition of LoA that I believe in. It connects our soul contracts and the best definition of karma that I have seen. As discussed in my https://medium.com/channspirations/revisiting-karma-and-the-law-of-attraction-997965601b65, DL Nemeril wrote regarding karma:

"Here, we would like to add that we do not agree with karma meaning you have to ‘pay’ for what you did in another lifetime. That is a very human perception, of life being a court system meting out reward and punishment. Karma is a vibrational level that draws the experiences needed for healing and growth to a soul. Nothing more."

I realized from that: "the law of attraction describes the vibrational pulls of our soul contracts, not what we humans consciously or subconsciously emit."

Getting back to manifestation, an underlying flaw is that the belief that the universe will help us manifest our desires as opposed to what it thinks we need, or to put it another way, if our desire is not good for us and/or we won't learn something from receiving it, why would our guides and/or angels help us receive it?