I think a better analogy than building construction is cars. You need to do active maintenance and fix things on cars to keep them running, you may even change out a radio or wheels, etc. like minor feature development, but you're not likely to change out the design of the engine and transmission. You definitely don't need the design crew from the car manufacturer around, aka Product Mgmt, to do maintenance but you do need some semblance of a tech team or people that can do the tech work on contract.

At some point a tech product is "finished" as in a mature, stable product and adding new things to it isn't going to do 10x in revenue. Its probably really hard for the product and tech teams involved to admit though.