The past few years have certainly provided mountains of coal to shovel into my cynicism train's engine, but I am not quite so far gone to believe this entirely.
Your point is true of many people, but I think even more do want good information and there is the possibility to improve journalism going forward. Snopes is a good example that fact checking is useful, desired, and can help drive consensus. I can't count the number of stupid Facebook threads I've seen get resolved by a Snopes link.
Your concern about the first-order effects of this are valid. If we're very lucky, the second-order effects may prevail. Yes, shady news sites won't want to be validated by Credder at all, leaving only better news to be critically examined and thus potentially undermined. But, if the system works, the absence of something like Credder on an article may itself become a signal of disreputability.
The odds of this panning out are slim, but I think it's important to keep trying until something works. Democracy cannot function without citizens having accurate, relevant information in their heads.