"Affordances" are a UI design concept - they're things that the design of an object makes you think you can do with that object, if that makes sense. In this context, door handles afford being pulled (because they stick out of the door and you want to pull the door, so you pull the handle), buttons afford being pressed (because they are small, often labelled with a function, and project above the surface they're embedded in), etc.

So yes, I think you're right that it's a word-play between the UI design concept and the cost of implementation concept.

And in the modern UI, all those small "hints" at how the interface can be used are being steadily removed: links, buttons, text fields, etc. all pretend to be static text.

Given that affordances is defined as "the quality or property of an object that defines its possible uses or makes clear how it can or should be used," I think it refers to how modern UI designers obfuscate the entire power of a system behind easy to use functionality that is aimed at mostly non-technical users, leaving those who have the capability to mold it to their preferences and customize it at a disadvantage. I guess affordability is then a word play on affordances.

Also - second definition here https://dictionary.cambridge.org/dictionary/english/afford

formal - to allow someone to have something pleasant or necessary: * The hut afforded little protection from the elements. * Her seat afforded her an uninterrupted view of the stage.