The scanner did tell him what the issue is. The scope would tell him which component is out of time instead of hours wasted tossing parts and not correct the issue. These are the tools of the trade now, you need to stay up to date or step aside and take it to a "pro" .
And if you think all of this is "new", Sun made engine analyzers with scopes decades ago.
But people with lots of experience with a certain type of engine can be a pro and the excellent diagnosing without all of the top-of-the-line equipment.
I have never been one or supported throwing Parts at a problem. I have to know exactly what it is before I repair it. I know sun made those giant almost like a wall analyzers but then they combined it all down into basically a handheld unit. This is why I was happy that technology that the cars had was making it easier to diagnose but now it seems they're going the other way.
I'm just not a fan of the new wave of intensifying things on cars when I don't see it as necessary when it's only a little bit of miles per gallon. I wouldn't have anything new the they make today. I would rather have let say brand new 2002 or 2003. I don't want the extra technology and its problems that the new ones have I just want a 2003 that is brand new.
You could have applied expensive Mac and Snap-on 6 and 7000.00 scanners or large dealer analyzers to a standard 4.6 or 5.4 Circa 2002 but it's not really necessary.
The basic check engine codes tell you all you need to know to fix most problems. Then we have the Lost Art of actually doing compression tests that many techs have never even done. The dealers perform a cylinder balance test which is similar but a compression test and canceling out cylinders will tell a lot to someone with a lot of experience.
But it is all a cycle like cops and robbers like radar detectors and radar units. They come out with new technology similar to OBD and OBD2 and the tools and software is very expensive for a while but then it comes down to being a cheap scanner that for under $30 can tell you what you need to know. These new cars will be complex and advanced but when they're 15 plus years old prices should have come down on all the stuff you need to figure them out. I still think it's a vicious and stupid cycle.