The page preview (the thing you see when you mouse over a link) shows the first couple sentences of the linked page, but ignores text in parenthese. Some mathematical pages use parentheses to indicate ordered pairs and removing them makes the sentence unintelligible. For example, the Wikipedia page https://en.wikipedia.org/wiki/Completely_metrizable_space starts out as follows:
"In mathematics, a completely metrizable space (metrically topologically complete space) is a topological space (X, T) for which there exists at least one metric d on X such that (X, d) is a complete metric space and d induces the topology T."
In the preview this reads "...at least one metric d on X such that is a complete metric space..." which makes no sense.
