Some people, myself included, have more than one copy of a particular game. That is why the system allows you to add multiples of the same item.
Stopped by to say the same - (not surprisingly @ a video game collection site like this), A LOT of us have multiple copies of games that we like being able to list separately for various reasons...what you're saying & asking would take away all of our ability to do so; basically = that's not going to happen
Besides, what is it about adding items that you're finding cumbersome & confusing?
While, I think, everything here is pretty basic & streamlined...like anything else - it takes learning, practice, and getting used to.
I know that I (and I'm not alone:) certainly made mistakes & bungled plenty of shit when I 1st got here
All of that said - if you're unsure of anything and/or need some help & explanations...don't be shy about asking for help. This is a pretty friendly & helpful kind of community here so, ask away!