The default behaviour of BGP on Cisco devices is to assign a weight of 32768 to locally generated prefixes. As you suggest, this will cause any locally generated prefixes to automatically be preferred using the weight attribute. This means that the originate attribute for such situations would never be evaluated, and one can argue, that it may not even be needed.
First of all, this behaviour speeds up the BGP process. If the tie breaker between two prefixes is the originate attribute, you will not need to evaluate the weight, local preference, and the originate attributes to determine this. The router will determine this simply by looking at the weight attribute, making two additional evaluations unnecessary. In such a situation, you are correct that the originate attribute will never be used.
However, keep in mind that this is simply the default behaviour. You are able to change this if you like, and have the originate attribute make the decision. Note also that that the weight attribute is a Cisco proprietary attribute and has been added to locally adjust BGP routing in a simple way. The official definition of BGP does not include this, and thus for non-Cisco devices, the originate attribute will always be used.
I hope this has been helpful!