The question you linked may be open for a number of reasons:
- Nobody's closed it yet, maybe because everyone thinking of closing it sees there's no close votes on it and wonders if there's a good reason it's still open, and.
- It's slipped through the cracks.
- This is one of those borderline cases that particular SE site accepts. Some sites accept, say, product identification questions, even though they are not necessarily good questions.
It's also worth bearing in mind that each Stack Exchange site evolves its own standards for questions and answers, though all generally adhere to the common principles found in the Help pages.
This is a case for that community's meta, not Meta Stack Overflow. You should bring this up on the TEX meta and ask the users on that site why it's still open, and propose its closure, if you think it should be closed. They can then discuss it with regards to their standards of what makes for a good question. If there's a good or historic reason the question is still open (point 1), it will surface (and could be challenged). If there isn't one, the users may decide to close it.