IMO the fact that code tends to become hard over time in the real world, is even more reason to lower cognitive load. Because cognitive load is related to complexity. Things like inheritance make it far too easy to end up with spaghetti. So if it's not providing significant benefit, god damn don't do it in the first place (like the article mentions).
That depends on who thinks it's going to be a significant benefit - far far too many times I've had non-technical product managers yelling about some patch or feature or whatever with a "just get it done" attitude. Couple that with some junior engineering manager unwilling to push back, with an equally junior dev team and you'll end up with the nasty spaghetti code that only grows.
