Bullshit. Papers directly supported by funding/grants should, and usually do, thank/credit the sources. But just because someone funded you for one thing doesn't mean you have to disclose that in every paper you write that is remotely related.
Papers directly supported by funding/grants usually don't thank/credit sources (or maybe it's just so small that I never noticed it?).
It's de rigueur, and honest funding sources expect you to credit them.
In my field it's usually a paragraph right before the references cited. Sometimes there is also a Conflict of Interest statement, which I think is required by certain journals.