Thanks for addressing these. Yeah, such modularity of databases seems like the way to go about things. But with hived, we have all data chained together (maybe in the future that will change but it seems speculative to rely on that for making current irreversible design decisions). My main concern is the replay time, which actually for me was already like 1-2 weeks since I used a mini PC at home. If we keep things as is, especially if the chain gets some more popularity, we can get to months of replay time for this kind of hardware.
So then the solution becomes to go for higher-spec'd servers, but requiring that means less people able to afford to run one. It also means we are using hardware and energy consumption for completely pointless activities, such as allowing operators of thousands of accounts to spam the chain (doesn't all this bot posting, worth millions of comments, equate to mass spam?).
The other concern is that all app development becomes that much more time-consuming since you have to spend time very carefully pruning (which in itself requires good overall Hive blockchain knowledge, i.e. an impediment to new devs) to get to just the data you need, otherwise your db has too many records and you hit performance issues that in themself take a lot of dev time to address.