I think because thats why they joined this awesome forum. They get real life people with real life experience, like you, instead of the possibility of someone that just was hired and doesn't have a clue, says bring it in, send it to us, etc. if its a simple fix like a misaligned belt they may not tell you that, they may sell you a new motor. When you fix a problem yourself you then have gained valuable knowledge and understanding , when you have someone else fix it they have the knowledge and you have a bill every time it breaks.