I don't think it's so much goal post moving as a lot of us never claimed it buys elections. My assertion has always been that generally speaking if you want to be competitive politically you need to scratch the backs of elites to get the proper funding to be relevant in elections. It's not an absolute, rather that there is excessive corporate influence that undermines the political process
A couple of studies from Princeton
https://scholar.princeton.edu/sites/default/files/mgilens/fi...
https://www.princeton.edu/~mgilens/idr.pdf
A biased write up on some of the findings, along with references to other sources at the end
https://represent.us/action/theproblem-4/