Similarly, “the licenses on these libraries aren’t compatible with , so now we’ve just rewritten the hypothetical licenses to all be the same as the GHC license”. Again, not sure what is gained here.
Putting together a product with a mixed bag of licenses is not always a nice experience if you have a legal department that enforces compliance with some (internal) standard. Since GHC is already validated (because the idea is to introduce Haskell, or it has already been introduced), same license would reduce headache.