This becomes more useful with #24539.
This would be useful for Lightning nodes so that they can use Bitcoin Core in situations where they currently use Electrum.
For example, an LSP has many mobile users who all connect to the LSP’s Electrum instance to get information on whether their funding/commitment transactions have confirmed, etc.
Instead, they could be using the Core REST interface to retrieve this info, using gettxspendingprevout + @sstone’s PR.
A caveat is that resolving this issue might not get us all the way to replacing Electrum, because Core still doesn’t support an address index, which is useful for monitoring initial on-chain deposits from users.