Not really, no. I don't believe McCartney's best songs would have been as good as they are without Lennon's pessimistic criticism. Otherwise, McCartney may have become like Pygmalion falling in love with his sculpture, Galatea. Unfortunately in this metaphor, Lennon is Venus who solves Pygmalion's problem that the sculpture was not a real person. But I hope the point is made, which is that only through dissent does anything progress to excellence.