I would like to refer you to this Facebook update by PM Lee about the by-election of Bukit Batok.
He said, "DPM Teo and I spoke earlier. Now that the Budget is out of the way, we are calling this by-election to enable residents of Bukit Batok to have their own MP as we work together to improve Singaporeans’ lives."
What does he mean by that? The residents just chose their MP last year in 2015. Does he mean they were not "enable" last year? The only reason why they are "enable" to choose so to speak is because David Ong had an affair AKA personal indiscretion. It is not "enable".