Outside funding opens the door for conflicts of interest and corruption. The funds can be used to artificially gather support by directly or indirectly buying votes, promising something in return for votes, etc., and politicians have a massive incentive to legislate or act in the interests of the donors instead of the will of the people who voted for them. The negative consequences severely and directly undermine the credibility, legitimacy, purpose, and function of the democratic process.

Campaign donations are a clear avenue for corruption. The goal is always to reduce corruption, and in this case, being so facilitating and detrimental should be even more so. "Found outside spending exploded after caps" - This is an obvious expected result. The claim that capping donations redirects corruption to other corruption avenues isn't a rebuttal. Corruption doesn't just end because of one measure. It logically follows that when an avenue is blocked, people go for others. And, to suggest that capping donations will actually cause an increase in overall corruption isn't logical. "Corruption increased after a cap to reduce it" doesn't make sense. Also, it's misleading to say "spending exploded after caps" without disclosing total corruption. Furthermore, to claim that because donor caps cause a shift to other methods of corruption, therefore, the ban isn't effective, is nonsensical. It's like going to fix leaks in a boat, covering one, and then going, "Well, there are still other leaks, so let me undo the one I fixed.". There's no reason to expect that donor caps need to solve campaign funding corruption completely, and then, worse, when they don't do so completely, to conclude the caps didn't help at all and it's better to allow it. "Anonymous millions", "influence underground", "Super PACs" or "dark-money nonprofits" corruption exists regardless of the caps. Claiming that reducing avenues for corruption is worse than allowing them is again nonsensical and unsubstantiated. "Demand real-time disclosure", "transparent check" and other measures can be done with the caps; they're not mutually exclusive. Also, transparency doesn't mean less corruption. It can just be visible corruption. Giving a nice-sounding name to where the funds go, "diversity and equity initiatives" for example, has no bearing on their actual purpose or destination. In conclusion, how does it make sense to allow for an avenue for corruption?

"A fossil fuel front group pours unlimited cash into an anonymous super PAC" - Again, this already happens with or without the caps. Different forms of corruption require different solutions. Why can't other measures be implemented to solve this problem alongside caps?  "That's not cleaner democracy" - So because caps don't solve other corruption problems, therefore, it's a "cleaner democracy" to remove caps and allow for more corruption. How does this make any sense? "Caps don't stop them;" - Since when are caps supposed to "stop them" or not be useful at all? Why is no protection better than partial protection? "They just push money underground" - Yes, that's what happens when an avenue is blocked; corruption moves to other avenues. So what? Why can't other measures be invented to stop the other avenues? The caps help reduce corruption, limited though it may be. How would removing them be better against corruption? The argumentation of "Caps don't prevent enough corruption; therefore, no caps is better" is incoherent.