Just 2 "relatively" recent examples, Tunguska and Chelyabinsk, both which never actually impacted the Earth(disintegrated or exploded above it high in the atmosphere), yet caused large scale devastation on the ground. Imagine the loss of life if an asteroid similar in size( 20-100m) to those 2 hit a populated urban area.
I applaud the efforts, however theoretically rare these events might be, it could be a huge life saver one day if they manage to successfully deploy the technology.
If you don't try, you'll never succeed.
https://earthsky.org/space/what-is-the-tunguska-explosion/