I agree, I personally don't think it's a valid myth. As you said, the customer overall knows what he wants, and he doesn't want technical (or ideological, in the case of Free Software) purity.
I was just pointing out that because techies consider something superior (ergo the myth), it doesn't necessarily "win". Plus in this case I think it's really, really hard to argue that GCP is superior to AWS.
AWS is bigger and growing at least at the same rate.
I wouldn't bet on Google becoming #1.