If the site becomes influential, brands will be motivated to pollute the source data, ruining both the usefulness of Reddit for reviews and Reddit communities as a whole.
There is also the fact that as you become more influential the value of your influence increases proportionately. The offers for "selling out" just keep growing bigger as you grow more popular. It also becomes easier to convince yourself that you're not really "selling out" if you just take money for this or that. And, like any business, of course you do need to monetize somewhere.
It's just an unfortunate alignment that goes against the core thesis of the (great!) idea.
Aren't reddit reviews already influential, isn't that why the site exists in the first place? If you're right, then it follows that this is already probably happening :)
