Many of today’s mathematicians use

[RonPurewal]

A capability, by definition, is something that someone can do (= is able to do).

If the sentence said "Mathematicians can use computers", then you'd have an explicit description of a capability"”and thus a solid reference for "this capability".

However, the sentence just says "Mathematicians use computers". So, the reference of "this capability" isn't good enough for a formal sentence.