There the danger doesn't seem to be getting something that isn't the truth, the danger is stopping at something that's just true enough for a certain purpose, and no more.

Why is that bad?

It can be bad if you mistakenly rest at a local maximum in your results.

You take a theory that is close enough to being true that it gives you results. Let's say, you make $1000 a month from a certain theory of web advertising on your website. If you worked a little harder to uncover the truth, you might confuse yourself and go down to $500 a month. Yet if you worked even harder, you might make $2000 a month. The $1000 was a local maximum. If so, seeking the truth could help you find it out, if we assume that (on average at least) more truth leads to more results in solving real world problems.