It always comes down to what we each feel is important.
But then as we start this hobby most don't know what is safe and what we can ignore. Who shows up most often in the fish postings with sick fish? The new folks, in most cases. So while we can each adapt the rules as we see fit, it seems logical and prudent to me for us to follow the directions until we get a bit of experience and can see what works.
If you've ever taught somebody to drive you will see that there may be times to ignore the rules but not when you are learning how to drive.
You can get away with totally ignoring the water treatment if you know how to deal with sick or injured fish and ammonia spikes. But then if you have spent lots of time and lots of money to get nice tank equipment, fish and plants, would you really want to ignore something so simple as doing water treatment the right way?