then, if you want to bloom, you can do it on the device or service, in any way you see fit. I did think about it a bit tho, directly serving blooms, but the reality is, the scores might matter more than just a true/false type thing and, it wasn't that much savings.

They do, and I think individual scores will always be there. But downloading 100K individual scores takes a while, uses a lot of data and space in the disk of the phone. Having ways to minimize that usage while providing some rough level of trust enables some light clients to exist. For instance, a user search or tagging could use NIP-50 to download all the shit on relays and then filter by local bloom filters to know which users are real ones. If bloom filters are not available, then the app needs another round trip to download the individual scores of each key and discard them all when the user closes the search screen.