So you have a situation where someone (you don't specify if it's the original author or some passing editor) takes the time to follow the link, suss out whatever is relevant on the other side, and write up a description of it that transforms what was before no more than a placeholder into something useful...
...and you're upset that this trumps the three seconds of your time it took to flag?
Don't be myopic about this stuff. The sort of effort you describe is rare, but wonderful to see when it occurs. Rejoice in the outcome, and take satisfaction in knowing that you may have had some small hand in motivating it.
FWIW, there is a third flag outcome ("disputed") that is used in cases where the system believes that the community disagrees over the validity of the flag; this is mostly triggered by /review/low-quality-posts, so if you wanna see it used more then encourage folks to use /review.