These streaming services are not worship-centric, and therefore won't ever be able to provide the kind of categorisation that Unified Praise provides. For instance, Unified Praise allows you to search for songs that are linked to a specific Bible passage, or songs that are based on themes like "lament" or "communion".
Unified Praise doesn't intend to compete with other streaming services, and doesn't expect exclusivity. Instead, Unified Praise aims to specialise where the other services can't, by being entirely focused on worship. With a major streaming service, worship music is a drop in the ocean, and finding something matching a particular theme or Bible passage is practically impossible. Unified Praise is a solution to this problem.