DeFi may have initiated a new hype but the concept of crypto lending is not new. In fact the first few waves of ICOs did have a bunch of Ethereum tokens that were associated with altcoin-pledging and using it as collateral for a bitcoin loan. Much like the services provided by the Sharks in the "Lending" section of this forum.
However tokens like SALT came to a stalemate(?), Nexo worked out it seems and partnered with many other sites like CMC and etherscan.
There is an analogy with fiat loans where you pledge a valuable to get a fiat loan. I dont see much difference apart from the subtle technicalities.