Can you explain to me why a reviewer funding a dev's Kickstarter or Patreon is considered corruption? Isn't that the reverse of normal corruption, where the beneficiary pays the corrupt?
I don't know if people would say it's corruption, exactly, but I can see why people might be uncomfortable with it. There is a possibility that a writer could feel an obligation to justify their support and be more positive than they would have been otherwise. There is also the possibility that a writer could feel jilted if the game doesn't live up to their expectations and be harsher on the game than they would have been otherwise. Whether it's positive or negative, any influence on a review that doesn't come from the game itself is considered a no-no.
Some people think Patreon is different from Kickstarter because it is ongoing funding of a project instead of a one-time lump sum, but I don't share that belief personally. Funding a project is funding a project. A dollar a month for ten months doesn't seem different enough from $10 up front to warrant a distinction.
What the issue of crowdfunding support ultimately comes down to though is whether or not you trust professional critics to be professionals. If you do trust professionals to be professionals then crowdfunding is a non-issue. After all, if you support a crowdfunding campaign it is not an investment, you do not receive any financial kickback if the game is successful. A professional should be capable of being self-aware enough to self-edit those two potential influences I mentioned out of their writing. There isn't a whole lot of trust going around for game journalists these days though, so it has become a hot button issue.