The problem with your argument is, since you haven’t taken the course work to become certified, you don’t know what you don’t know. I too use Google when I’m at a loss for what to do, but I at least know what I’m googling. I have an advanced degree in Mathematics from a German university. That, by itself, doesn’t make me either qualified or competent to teach Mathematics to teenagers. That’s not to say I don’t need formal training in Mathematics, but it is only one element of being qualified.
Have you had SAFE training, or something comparable, which would teach you to recognize unspoken suicidal ideations in a child? Have you been trained in delivering services to students with a Specific Learning Disability, or a mental illness, or an emotional disturbance? Have you been trained to recognize the signs of emotional or physical abuse in one of your students? Have you received training in how to deal with such a situation? Can you recognize the sometimes subtle signs of bullying, and do you know how to respond to them? Do you have a legally acceptable strategy for dealing with misbehavior in your classroom?
Being able to deliver an engaging lesson is just one part of being a competent teacher.