Link text is wrong: the article claims that most short-period binary stars merge to form a single star, NOT that most single stars were formed from the merger of a short-period binary star.
Link text should have said 'Many' stars are born as two separate stars. That is consistent - it's not clear to me what proportion of single stars started off as binaries - probably not 'most', I admit. The implication of the paper, though, is that many stars around now that we think of as 'single stars' started life as binaries.