The main problem that I see in my years of experience is: "how well does what I design hold up to ACTUAL product design changes?" Everything else comes second

The main problem that I see in my years of experience is: "how well does what I design hold up to ACTUAL product design changes?" Everything else comes second to that including this authors version of "build extensible systems around dependencies, this allows you to shift dependencies without shifting internal logic." That idea is good as long as you dont end up rebuilding an entire framework out of that extensible system, otherwise you shouldve used an existing one. If you have an extensible system, but dont use it, thats a lot of complexity that increases the maintenance burden. All of these tradeoffs make sense in their appropriate circumstances, but those circumstances largely rely on predicting the future of the product IMO.