I'm not following you, that quote basically says what I said.
Grin creates more fungible coins as it destroys the links (transactions) automatically but you also have a trade off by not being able to prove a past transaction.
I'm not sure what effect Monero's pruning will have but I think there will still be full nodes with non pruned chains. TBH I don't remember and am not going to go an re-read it.
Lets reduce to this
Basically, Monero has three privacy protocols. Ring signatures, stealth addresses, and ringCT. However, stealth addresses and CT are the only parts that are absolutely essential to privacy. Ring signatures are great for the paranoid, but they actually arent completely necessary. Theyre wonderful, but theyre also redundant. Grin strips these away and leaves only stealth addresses and confidential transactions. An observer still cant derive any useful information from a Grin transaction, and the fact that Grin allows transactions to aggregate, or merge together, makes it even harder to trace.Monero have 3 Grin 2. Blockhain analysis will break through. Maybe they will fix it. If they will maybe that will be Monero next solution.
This is actually first time I am reading someone propose that grin is less traceable as Monero. Here is what someone else says:

