How do you want to make sure, that those 10k coins are not created out of thin air, without fully validating the chain?
Here's another argument against gigantic block size: If the blockchain grows faster than the rate you verify transactions, you can never reach the chain tip on regular hardware.
As reminder, vMB and MB are 2 different unit. Maximum block size is 1 vMB or 4 million weight unit, where theoretically a block can reach almost 4MB in size.
They are two different units, but we've softforked to vMB. It'd be wrong to measure things in MB, since there's an entire field which can handle more information than before.