Spark/Ark are necessary for plebs to build useful/novel bitcoin apps as liquidity management (woes) are too high for getting users onboarded unless you’re also in the business of continually managing navigating all that on the backend, or paying though the roof to an LSP (and still having to manage all that). You can slap Spark-Ark sdk in your app and you’re done, you’re now opening up the Bitcoin eco system to x number of new normies.