Yes and no.
Yes,
- I used your tutorial and added this one command.
But no,
- Basicly the thing we do in item.dat is also a simple command.
- Things change when you try ingame commands. And I described them as you did.
Also I didnt describe modelling parts. So this tutorials purpose is just making items shown in game. Which can be helpful to people who want to import their models ingame and easier to find.