Use case or problem
Obsidian designed in a way, that encourages creating more files, rather then larger files
BASES only increase that effect.
this is not a problem in of itself, but there is no support in global filtering/limiting viewed files and so on.
Even Quick switcher can not filter them, beyond de-periodising,
and search queries, dataview queries and everything gets slower with more files.
Current status
I am currently using nested vaults
meaning I have vault one and then one folder inside is an another vault and so on.
it means all files of that vault can be opened in two vaults
that works, but it has flaws, most obvious is that I need to use system links to attach folders beyond the straight tree and so on
Proposed solution
since ability to use Obsidian to open .md files outside of your vault appeared in the roadmap.
it is not impossible to also add ability to define any folder as “sub-vault” and allow to mount it at any number of other vaults
meaning in the obsidian vault selector, there is not only create new vault, but also “register new sub-vault” and so on.
Alternatively
an vault nesting can be supported, allowing one vault include any other vault wholesale, if that is for some reason an easer solution, but that creates a lot unnecessary metadata.
Current workaround
System links do technically allow to do that
but they are system level, hard to maintain, not portable, and do not work across operating systems, a native solution would be much better.