How many times have you come up with an idea for a scenario and developed it, only to be beaten to the punch by someone else´s design?
And how did you react? Did you drop it or keep going?
The Monkeys with Typewriters contests stemmed from a discussion about the portraying of the Tardijksfjell battle (Norwegians and French vs Germans in 1940) by three scenarios.
My take on the question is, as ASL is more an "impressionist painting" than a very precise simulation, scenario design has an "artistic" dimension.
The aim is not, as we say in French to "count the buttons of the gaiters", but to produce a fun scenario, which gives the feel of the historical situation.
This means selecting significative details
and ignoring others.
That analogy can apply to historical books : the angle of approach allows to have several books, say, on Barbarossa.
In addition, the small surface covered by the typical ASL (about a square kilometer or even less) means that we don't often have access to that level of detail.
When we read situations at batallion (or division, or corps...) level, there is a lot of space for adaptation and imagination.
The "variable OBs" in some scenaros could reflect the partial fuzziness of the data at low tactical level; and they are welcome: they allow more replayability and you have the pleasure to "choose your toys" (a satisfaction not to be neglected).
Besides that, historical events have no copyright.
I would say that designers covering the same situations offer different ways to get the feel of them.
It would be sad to refrain from publishing a scenario because someone else has also worked on it.
TL;DR : scenario design is an art, so I am all for different pictures of a given historical situation. Historical plausibility must be conjugated with a good, immersive fun factor.