Because such texts shouldn't interfere too much with the portrayed designs. The typography needs to be as neutral (read: boring) as possible. It's like putting up a collection of various high-key photos on a grey background; because you don't want the overall information or environment to become a distraction.

However, I do think it would be a better solution to find a font that kind of connects it all together, and which bears something of the designer as well.

Some one here at Quora recently pointed out the Barlow font to me, which is absolute pristine for a job like this !

Oorspronkelijk geplaatst op Quora: Why do many high profile designers, artists and architects use the most default typefaces such as Arial and Times New Roman in their work or on their website?"