It might not be necessary to produce a proof of concept and instead go straight to a prototype.
The decision to develop a proof of concept or go straight to prototype development is dependent on the risk associated with developing, manufacturing, marketing or the technologies associated with a product or service. Often a prototype will be sufficient to take to market or put into service.
The cost of product development and the time to market are often critical. Consequently, it's sometimes more effective to identify the minimum set of features and specifications that make up a commercially viable product, system or service and first develop this - often referred to as the minimum viable product or MVP.
Another way of looking at this is that we are looking for features that can be left for a future version of the product so that we can get to market sooner.
Delaying or reserving features also allows us to plan future versions of a product and create a product roadmap, or a product range.