because of a little, tiny designation this virus was given when shit hit the fan and public health policymakers realised this was a global problem:
novel
"Novel" is how epidimielogists, biochemists, doctors, and the rest of the scientific community functionally indicate to the world the following: "We have exactly no fucking clue what this is, how it works, its short term effects, its long-term effects, how to treat infected patients, or how to prevent its transmission." all implied and wrapped up from saying:
this is brand new, we haven't seen this before.
So, what do you do when a virus you really don't understand starts spreading worldwide in an effectively uncontrolled measure? You take action to stop
transmission along the vectors you know. Thus the masks, quarantine, social distancing, and hand sanitizer literally fucking everywhere. Do the masks work perfectly? No. Does Social Distancing work perfectly? Pretty close, but also no. Does the Sanitizer work perfectly? No. Are they about as good as we've got at this stage? Yup.
What do you do about already infected patients? Thoughts and prayers they survive and then study the survivors and the dead as the situation allows. This is the step that takes years because there is literally no other way to study the long-term effects than to wait and see what develops. Thus the attempted measures to stop transmission occur. (At this point, don't come at me with "well that didn't work" especially if you're one of the lot that decided not to follow such procedures because the world gubbamint trying to oppress you, snowflake.)
"But it's so mild!" We didn't know that at the start and we still have no idea about the long-term effects of infection, so we can't say that accurately. The point was and remains, that the policymakers are going to err on the side of caution such that they can't be held accountable for doing nothing, which in their estimation, is better than being screeched autistically at for trying to do something.
Then we get to the government. Why did they crackdown trying to enforce these meadures so much? From a policymaking perspective: fucked if you do, fucked if you don't. If you do, segments of the population get big mad, an economic hit is taken, and you risk some unrest. If you don't, and especially if you don't and this is a cripplingly devastating virus, you've got blood on your hands and a much MUCH larger swathe of the population is big mad to the point of possible, serious political destabilization. So what do? Enforce the measures, risk some people getting pissed off, but at least a destructive virus didn't run completely rampant through the population on your watch. Cost v. benefits enforcement is the prudent choice and once the eggheads catch-up with something you can administer and then wash your hands of the situation with *coof coof* vaccine *coof coof* you can at least say "I tried" and for the most part, deflect a lot of the possible anger that would lead to the serious instability.