The original point was that you become reliant on a public service, probably run by volunteers, for something halfway critical to your operation. Doing it yourself is easy and then you control the reliability, not someone else.
You're just saying things that don't have basis in reality.
It's not something halfway critical to the operation–why would the FAA allow that? ADS-B Exchange is not run by volunteers–it's run by employees of JETNET LLC, an aviation intelligence company. Doing it yourself almost certainly gives you less information–you're not part of a global network of receivers. It almost certainly gives you less reliability–receivers in the big networks typically have a fair amount of overlap which gives redundancy your single receiver doesn't have.