This is actually very similar to how semi-custom cabinets are made and sold, aside from the web interface. There is a catalog of available cabinets, and each cabinet can be customized in a variety of ways. For example, you can order a drawer + cupboard base cabinet with 2 roll trays and finished left side. The cabinets are built to order, but from a standard set of parts. They're built in a factory and shipped to the job site fully assembled. (One big maker is Masterbrand, which like GM offers many similar products under a variety of sub-brands.)
Instead of the web, though, cabinet selections are typically made by a kitchen designer, because the customer is not sufficiently skilled to take responsibility that the items ordered will actually fit. This might be a problem in woodworking, though perhaps less so for furniture.