It's much harder for an airline to assess someone's training record if they have been to the US for their CPL, then back to the UK for an IR which they started with one school and finished with another.
Well, that should stop all Oxford students then - especially as they have done, in essence, a modular course (even though it's dressed up as an integrated one).....and Oxford are keen to point out (for various legal and financial reasons, that the USA and the UK are two totally seperate companies).
They even use the same instructors, same aircraft, same examiners, same test routes, yada yada yada for the modular as they do for the so-called integrated.
The only differences between the two, at Oxford, are the price and the title of the course.
The entire industry is smoke and mirrors - doesn't matter what and how provided it looks OK on paper.