Correct! The main benefit is that you can create a web/mobile application which makes use of Lightning invoices but delegate the tx infrastructure (signing, route finding etc) off to a service provider (e.g Bluewallet).

If you're looking to push further into the mobile world, but would like full node capabilities, BDK and LDK both support Compact Filters (https://docs.rs/bdk/latest/bdk/blockchain/compact_filters/index.html) to implement BIP157. That means you don't need to download the full chain but also don't have to compromise on validity.