Who is spamming the bitcoin cash mempool and why?
It is not too difficult to check the low-fee transactions in large blocks with block-explorer. Follow the link 
https://blockchair.com/bitcoin-cash/transactions?q=block_id(479479)&amp;s=id(asc)
and press Load more... link several times.

There are a lot of one-input-to-one-output dust transactions like https://blockchair.com/bitcoin-cash/transaction/2ad1135d02924336901d23179d41a74a800da4f2247cf9e66e4cdccf8656f10c

So, this looks like spam. Sorry, I do not have any more information about the creator(s) of these transactions and their goals. You should investigate yourself. Hope my links are useful