There's plenty of approaches to do things inconsistently. The effectiveness will vary, but wont necessarily improve on what Primal is doing. Primal's approach is a tradeoff to improve some aspects while using the app, in exchange for missing data that it hasnt cached, and allowing more centralized metrics gathering on whats been viewed. It's a silod platform and there should be little expectation of it letting users see all the relevant nostr data that they would potentially see with other nostr apps. If its important for users to see all posts, replies, and zaps then I would not recommend a caching platform like Primal. It's more akin to Facebook or Twitter but attempting to be eventually consistent on a single pass of relays where there are no QoS contracts or guarantees in place. Indeed, relay operators for which Primal reads from for its cache should consider fee for access if they arent already. This is a bit similar to google and indexing and serving content from news outlets