I never understood that narrative either. You won't get high quality information from someone that is paying you for influence. You will get a lopsided/biased perspective, and the unwritten expectation is you will use it or contributions will cease.
Congress can and does ask companies for their expertise/stance on any given issue or policy, for free. They want to be involved for the same reason they lobby.
The same could be said about the judicial system though, right? Both the prosecution and defense are paid to influence the judge, and will naturally provide a biased perspective. But that doesn't mean there's not high quality information within.
I don't think biased information is a total dead end, but the onus is just on judges and politicians to tease out information from more than one angle. And often they don't.
It's up to the congressman to weight all evidence and data available and come to well informed conclusion. If they are incapable or unwilling to do that that's a different issue.
> Congress can and does ask companies for their expertise/stance
They are inherently incapable of identify all these companies or measure the impact of their policies on their own, though (which is perfectly understandable, well I guess these days they can use an LLM to make this easier... /s)