Loop is for channel rebalancing.
Loop-Out: You have all the LN balance and want to get rid of it. Send LN payments routed through your remote node to a party who will give you BTC off-chain. BTC transactions can be coalesced to reduce fees.
Loop-In: You have no LN balance and need more. Send someone BTC off chain and they'll send you LN payments route through the remote channel point. Eliminates need to close channel.