The W would disambiguate the kind if there's any collision, so you could reasonably query for the NIP-85 structure and find attestations that might be available where you don't necessarily know or care exactly what types they contain

zap_sats_sent would be a good type in my view, rather than just value, zap_sats_sent would be better having values under it... perhaps things like week month year. So yea to your point I don't think value is itself is a good top-level type example, I mostly like eliminating the registry in the NIP.