I don't know a ton about Patreon, but it seems like a service where you are really supporting someone's work on the basis of who they are, rather than what they might produce in the future. That may lead to smaller numbers of supporters vs. a service like Kickstarter, and in the case of independent developers and gaming writers, a lot of their friends who might support something like that (even as a symbolic trading of back-rubs) are likely to be other independent developers and/or gaming writers. So when I hear that a PR rep backs a writer's Patreon, that sounds like friends supporting each other. I don't think anyone honestly thinks a $5 donation can influence coverage... but yes, it can have the appearance of impropriety, especially when (by definition) you are not even paying for a product.
Kickstarter is much more of a gray area, and we had a good discussion about this between recording RFN segments last week. I firmly believe that Kickstarter is not an investment platform, because you legally cannot see a financial return on money pledged to those projects. So that's what it's not. What it is, depends on the kind of project you're backing and how much you put into it. For video games, I never back anything over the "get the game" level. So yes, it is a de facto pre-order. Normally, I don't support the concept of pre-ordering games because scarcity is no longer a real issue, and because it's more advantageous to the consumer to hold your money until the game is actually available (and subject to critical analysis, among other things). Pre-ordering a retail game doesn't even really support the game's development, which is often very advanced or even complete by the time pre-orders are available, not to mention that your down payment is just being held by a retailer (in escrow!) and will never been seen by the developer or publisher. However, pre-ordering a game on Kickstarter has a tangible effect on that game's likelihood of being completed. If I see an interesting game listed there, it makes sense to throw a nominal bit of money over to some small developer to help bring that game to fruition.
Ethically, I don't see this usage of Kickstarter as being any different than a game reviewer pre-ordering something at retail. You might pre-order a game that you're assigned to review, if you're concerned about getting it immediately upon release to help make your coverage timely, or if you need to review exclusive pre-order bonus content, or for other legitimate reasons. All it means is that you intend to buy that game. It doesn't necessarily bias you towards or against the game in any way. If the game ultimately sucks, hey guess what, you paid for it the same as all your readers who may feel exactly the same way. So I don't see how any of this invalidates or even throws shade on a member of the media.