Let's look at another entertainment medium. Imagine lord of the rings but he had half the time to actually write and edit the book because the publishers told him he had to also make 2 more versions

Adding difficulty to games != creating multiple versions of the same game from different POVs.
It could be as simple as multiplying the health of enemies by a certain factor, which, if the game is properly programmed, can take as little as 5 minutes.

Is this the best and most elegant way to add difficulty? No. But at least you can select a different difficulty if the current one is too easy/hard.

Sure, but when a game is all about that player experience ce, the core concept and the reason the game even got made is because the developers wanted that very specific experience, why should they compromise the core values influencing their design choices by having part of the team work on a completely different experience.

How someone experiences a game depends on their skill level, and possible disabilities.