Re: your definition of Producer:
If I buy a Dell computer and re-sell it as an integrated, but separable, part of my product/system, are you saying that I am responsible for WEEE compliance of Dell's computer? I have been advised that since Dell's name is on it, Dell is responsible for it.
Dell could be responsible if you worked it out with them (subcontracted this responsibility to them). However, the EU will look to you to make sure it gets done.
Look at it another way. Say you purchase Dell computers and don't tell Dell you are shipping the product to EU countries, how would they know to recycle them? So I stick by my original position, if you "put a product on the market" you are responsible for all of it Re WEEE.