Why will those factors not be applicable to crypto? (People taking custody of their own cryptoassets may mean that the exchange can't lend them out, but as exchanges continue to pass the test of time more and more people may be willing to leave assets on exchanges.)
AFAIK the only reason why there's a market for lending stocks is because the SEC prohibits naked short-selling. If you want to short-sell, you need to locate a share somewhere and "borrow" it, which leads to brokerages offering to do that for a price. For crypto this isn't required because you can short using CME bitcoin futures, which is cash settled and therefore doesn't require you to locate/borrow anything.
On crypto venues you can spot borrow crypto but there you're right that there is not much demand for this, and as a result lenders don't get paid much.
