That is called "luck". I too was lucky for the first dozen or two batches.... until the one batch when I was unlucky and it was Band-Aid crazy and I had to research to find out how to prevent it.
Those of us who are plagued with a engineering mind recognize "luck" as "probability in action", and I believe there's a lot of it in brewing. Just about every step in the process has some small chance of resulting in failure, and good (successful?) brewers do their best to minimize the worst of those chances.
There's some probability, say, of me getting away with poor sanitation procedures, and still producing pretty good beer. Until I hit that bad result, I can blithely claim that "Sanitation doesn't mean squat - I never clean my fermenter, and I haven't gotten an infection yet!" Of course, "yet" is the operable term - it's really only a matter of time until I do get an infection that exceeds my threshold of perception.
Same idea with stuff like adding campden tabs; assuming my water has chloramines (it does, by the way), I MIGHT be able to get away with not treating it for some number of batches before "luck" bites me on the butt. But bite me it will, eventually. This goes for lots of our brewing processes - water treatment, mash temp control, fermentation control, etc. You can certainly ignore the probabilities involved with sub-optimal procedures, but eventually you'll get bitten.
Some of the probabilities of failure are pretty big, and some are relatively tiny. And the solutions can range from dead simple easy, like adding a campden tab, to much more complex, like minimizing oxygen issues. Every brewer decides for him/herself which to address and which to ignore.