It's surprise for me that there are still non-opensourced MS-DOS versions. Why keeping them closed?
And I see no reason not to opensource early Windows versions (up to 2000).
And I see no reason not to opensource early Windows versions (up to 2000).
Of course one could say that Windows 11 provides negative value, in which case running DOS 1.00 would also be better ;)
Also, getting the source code for external libraries was not common until open source became the norm. Making something open-source often requires rewriting parts of it.