I don’t know about you OP, but when I booked my wedding, I booked it for myself and my DH, I didn’t ask anyone else what date worked for them.
Had family had holidays, graduations, births or work commitments that really didn’t come into it, as it was MY wedding. If they didn’t want to come that was their choice. For you to suggest that Harry and Meghan arrange their wedding to accommodate William and some footie match is beyond ridiculous!
I’m sure when you’re marrying a royal there are lots of invitations already booked into the diary, so they probably arranged it for a date when the queen or prince Charles didn’t have to let anyone down.