It's a little bit over-simplistic to think that, if you're a Web developer, you "just" select RESTCONF as the protocol, as opposed to NETCONF.
Our customers will anyway decide but should make an information decision, so let's ask them the right questions, coming from RFC3535. This RFC is 14 years old, but the operational requirements in that RFC are still valid. This spreadsheet compares how NETCONF and RESTCONF fulfill the RFC 3535 operational requirements. And you will see that RESTCONF lacks some features compared to NETCONF: no transaction hence no two-phase commit transaction, no lock mechanism, no <copy-config> equivalent, no validate.
In summary, NETCONF should be used for network elements configuration (required for easier management for a tool like NSO), while RESTCONF is more appropriate as a north-bound interface from a controller or orchestrator). RESTCONF will however be available on IOS-XR 6.2.1