Well it's clear the OP has his mind set on his opinion. This is/was not a dialog. The P-51D was made as a side project, so it didn't detract from the making of other modules. Various teams do various projects because that's their desire; you can't grab them and 'unifiy' them to do the current era etc. using the fragmentation POV reasoning, because they don't want to, simple as that.
For the "discussion" (i.e. rehashing of the same original fragmentation points of view) to continue, the OP must ignore repeatedly this aspect. It simply has to be how he says: the fragmentation exists, and is detrimental to the sim. The argument will be won by sheer force of determination and repetition.