Exactly. It could be useful to receive some smaller amounts by forming some kind of CPU pool. For example: if mining 1 BTC needs a lot of power, then mining single satoshi is 10^8 times easier. Then, if there are many clients, that could be promising somehow. "Cloud" or "pool" mining operator can just receive shares and send payments in this "LN-like way". Sooner or later, millions of such miners could produce a block.
The trick is to produce a block with your CPU pool. My ASIC would outpace probably thousands if not millions of actual PCs. A pool wouldn't pay out unless they generate a block that is why PPS is usually for more established pools because they can afford to pay out the funds in advance while smaller pools pays out in PPLNS.
Most cloud mining websites, or at least those legit ones takes in deposits for contracts to cover the running costs of their ASIC farms. If the funds gets locked in the multisig, then there is no way for them to pay off their expenses in the short turn and they might as well just mine for themselves. There is a reason why they sell their hashpower and that is to eliminate the possibility of profitability loss due to exchange rate or difficulty changes. Locking them in a 2-of-2 multisig with no mediator is dangerous. Either party could refuse to sign a transaction and effectively holding one another hostage over the funds.