[noplacelikehome]

Two reasons I can think of: it wastes your time to have keep scrolling past blatant hallucinations, and it still costs the environment to compute it. I'm happy to cost Google some money, but I'm less happy about the environmental impact they'll inevitably not pay for.

[ryandrake]

The over-arching good reason is simply: I don't want it. That should be good enough! As the user, I should be able to command my computer to output what I want it to output, and to not output what I don't want it to output. The user should have the final say over what computation does or does not happen on his computer, not the web or application developer. And we don't need these "Take it or leave it" ultimatums from developers. Using a computer should not be some faustian bargain, where you have to sacrifice something in order to have it precisely follow the commands you issue.