Sure , I believe that everyone whos got a little mechanical ability should do their own routine maintenance if they choose to, but getting beyond routine without the knowledge and proper tools is a recipe for disaster. Most wrenches, myself included, have had to undo a backyard hacks 'work' in order to fix a problem. and most will not even touch a car that is brought to them in boxes, without an agreement that Im not liable for any damage done by said hack, and that the repair most likely will be far more expensive than if Id have done the job in the first place.
That doesnt even get me started on the dangers of unwittingly working on brake or steering/suspension systems that can be deadly to the wrench twister or innocent bystanders if improperly repaaired.
Or the possibilities of electronic component destruction by ill advised test procedures on computer controlled cars or the possibility of destroying major engine internals by improperly timing a non-free wheeler valvetrain in a 'simple' timing belt job etc etc etc
IOWs, choose if you want to save some $$$ on car repairs, choose your battles wisely, and if you have trouble with things like changing a lite bulb or programming a vcr, you prolly out to leave car repairs to someone whos had a little more than a course on internal combustion 101...
I just bought a '98 Voyager for $1200. It needed no work but I discovered the interior lights didn't work. I traced it to the headlight switch. I took the switch apart and cleaned the internal contacts and installed jumper across the bad contacts. Everything works except for the defeat part. I would never recommend to anyone to try this at home. My job is an electrical technician on printing presses. Without that expertise I would have ended up spending $300 for the diagnosis and repair.
Working on cars has become very difficult but it's still worth the time if you can do it.