On this subject, it really annoys me that many scientists seem to think that "data" is a plural noun. They say things like "these data support my findings" instead of "this data supports my findings".

Data is a non-count noun. Nobody ever talks about "a datum". If you have something that supports what you're trying to show, you talk about "a piece of data" or "a bit of data". Where do we see that way of talking about things? Non-count nouns. "A glass of water", "a bit of dust".