Use of product dependencies

After I've tested I now wonder what's the meaning of product dependencies (AccProductDependencies).

As I read the docs (and have tested), you can prohibit that someone could order product A and B together (IsExcluded) - but it is allowed in subsequent orders. So the feature is just to bug someone to create two different orders to achieve the very same result (that I try to prohibit)?

Same in the other direction (IsMandatory): If I have 3 products A, B, and C where C is dependen on A and B (so that C is mandatory if one tries to order A or B) I cannot order A alone.
That works (though I struggled to find the dependent product in the shoppingcart). But after ordering A and C, I tried to order B. And that's impossible at that moment. I have to order C again, but since I already have it, the shop refuses to do anything.
So this seems to work properly for two dependent products only - though the front end is not clear all the time (this little arrow in front of the row is very subtle).
In addition, I'm able to unsubscribe C after I orderd A and C. And again, I can achieve an unwanted result with just 2 actions.

IsOptional seems to work as expected - I just don't think that any customer will ever see the hint (and it's not, what I currently need).

At the moment I think it's just a bit more difficult to get results as before and impossible to get meaningful results.

This should't be a rant - I really want to know what I'm missing here.