Because you fail to see the contradiction.
You would not host someone in your house who was exposed to Ebola but not showing symptoms, yet you claim there is no danger in same.
Therefore you should be willing to host them.
But you won’t.
Why not?
Because if that person became symptomatic, then being in close contact with them (including hosting or living with them) would increase my risk of contracting the disease.
Whereas them being out on the street while exhibiting no symptoms does not increase anyone’s risk of contracting the disease.
Y’know what, you keep telling yourself there’s a contradiction. I’ll stick with the opinion of every infectious control expert who studies this stuff, and thinks that the right answer is no quarantine and no close contact. Again, I’ll also stick with history, which has proven them (and me) right. You can stick with your scared, chickensh*t view of the world.