All I heard was that the block size was not increased and this led to the creation of Bitcoin Cash. It was a fork but it is an altcoin (shit coin) while bitcoin remain the bitcoin.

But I am thinking recently that if the block size is increased, more transactions can be processed and the mempool will not be congested. If the block size can be in a way that 1 sat/vbyte transactions can all be processed in the next block, will this not be good?

If the block size is increased, what is its disadvantage to bitcoin network and miners?