The plague spread by sea ships back in the day. And said ships transported far smaller numbers of people than anything we've seen in our lifetimes. Lots of examples of contagious disease spreading also involved terrestrial transport. So, any form of mobility increases the chance for a contagious disease spreading.
So what? Shall we just confine everyone to only as far as one can walk? That's totally impractical on any level. So, the solution lies within better prevention and better preparedness for reaction in case the brown thingy does hit the fan. More research on viral and infectious diseases, more research on disinfection technologies and wide implementation of modern disinfection techniques, better prepared healthcare systems and promotion of better hygiene habits among the population could be some far more sustainable solutions than blank restrictions on freedom of movement.