GPS spoofing is no where near the same thing so I'm not even going to touch that. It'll lose it's magic without communcation and updates from them. If they can't fix their own tracking system people will go to other means. I'll have way more fun knowing where there is pokemon rather than hoping I bump into one of the 3 paws on my 'tracker'.Knowing about it is already killing it for me. This and GPS Spoofing. If these things get to the masses, Pokemon Go will lose ist magic...fast.
It doesn't matter if someone captures it or not, it spawns in for a set time then goes away, someone else using a map doesn't effect your chance up randomly bumping into.When a really rare Pokemon spawns, if it's snapped up by somebody who knows it's there, that means you can't then get it after the servers next refresh. Not to mention part of what makes Pokemon Go so fun is the social aspect of talking to others, which is cut out entirely if people are just making a beeline for the best Pokemon on their own.
So these tools can have an impact on you, even if you don't use them.