If you believe this is the case then you can put your belief to the test. Build software the way you think it should be built and see if users are willing to pay for it.
"users willing to pay for it" is a very bad and simplistic metric because there is way more to user willingness to pay for something than how that something was made (not to mention that it excludes everything the user doesn't pay for) - it may not even have to do with the software itself.
Also the software in question may not even be "free" to use the better approach: imagine, for example, a client for a chat service that allows embedding images, videos and audio in messages but the way the protocol works is for the server to provide those as iframe and/or html content. At that point the client will have to use a browser component in one way or another with all the baggage that entails even if the features themselves (images, videos, audio and text) could be implemented directly by the client.
There is only so much you can do when you have to interface with a world built on tech that doesn't care about efficiency.
Modern computers have opened programming up to more people by making it simpler but with the tradeoff of more runtime execution cost.
I believe the sibling saying that it's programmer productivity is correct. That same programmer can and does now spend a week whipping together a program in Python that took a year under the older constraints. And users expect more out of them, with whizz-bang animations and app-store integration.
But if that same programmer _did_ spend the year instead of the week, what could they do? The quality and performance would probably be a lot better. Unless they depend on externalities that don't also scale up their quality game, like basically anything involving the web.