Ok, so they do that. Here are some things that can plausibly go wrong:
Are the people posting the story funding thing anonymous? Because if they are, no one will fund it based on a one line description with no details. If the authors are known, any company engaging in the practice will be watching them like a hawk (essentially making investigation impossible)
The company engaging in the practice assumes the investigation is aimed at them and temporarily stops double billing until the journalists runs out of budget and everything blows over. They then resume double billing.
The company engaging in the practice assumes the investigation is aimed at them and consequently intimidates would-be whistleblowers into staying silent, basically preventing any progress
The company intentionally floods “Kickstarter for News” with spurious stories to drown out the item about them
The story isn’t funded because it doesn’t agree with the preconceived notion of enough users, who are only willing to fund content matching their own worldview
The story isn’t funded because, while people find it is important, more attention was placed on a story that agreed with the preconceived notion of enough users
What stories are funded have a huge bias towards the material condition of the wealthy (moreso than now), since they are the only ones with enough disposable income to fund content. Therefore, content focused on the conditions of the poor and marginalised is ironically marginalised
Unable to be subsidized by less prestigious entertainment content (like traditional investigative journalism was), the required upfront cost for stories balloons to a size not feasibly collected by donations
The wider population becomes apathetic to the platform as a whole (people have actual jobs and lives, and may not have the time to trawl through potential stories for something they want to fund), leaving only the extremely wealthy/powerful to fund stories. As a consequence the media is even more controlled by the elite than it is currently
It turns out there was never a story, and those that donated feel burned and are less likely to donate in the future
It turns out there was never a story, and, feeling pressure to produce something, the journalists intentionally misconstrue the truth
I think a crowdsourced approach is a great idea, but only in the sense that my tax dollars go to independent news organisations.