The prime meridian which is 0 longitude is, ultimately, an arbitrary reference. It was probably chosen due to its popularity as Britain had the largest fleet back in the 1800's and it was their reference taken from Greenwich Observatory.
Scientifically there is no basis for any meridian to be the prime meridian. It's basically a point of reference and one can choose any meridian anywhere on earth to be the prime.
So Mecca can claim they want to be 0 but the world has already agreed on Greenwich. Good luck changing that today. It would be a huge cost to reprogram all satellites , GPS receivers, maps, charts etc. etc.
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