Because western quarantine isn't true quarantine, and because what you really want to do is take every person who shows up with COVID-19 and then find out where they were for the last two weeks, and quarantine everyone they touched and do a proper quarantine on them.

But since that's not feasible, the alternative is to test as early as possible and hard-quarantine immediately -- by testing everyone constantly and everywhere, for which you really need sufficiently real-time results.

Right now, with soft-quarantine,the virus is still spreading, and the timer refreshing -- as soon as people are out and about again, rates will spike up again. Soft-quarantine is a delaying tactic (smoothening the curve), but not a solution.

But we also can't soft-quarantine for that long, because it's crushing the economy. If we keep doing it, there won't be much to go back to.

You need a test, and a fast one, or you don't have much