From my limited exploring this is mostly noise. For example, math lib is taken from recent sqlite and backported, useful only if your sqlite lib is more than 2 years old. Quite a few extensions are taken from 'ext' dir in sqlite sources. Others are redundant and trivial; why use a specialized cube-root extension when you can directly calculate pow(_, 1/3)?
Adding this collection as a project dependency would be opposite of "lean". Better to manually collect the functions you need, favoring the well maintained and tested sqlite code base over other sources.
I use sqlean for the same reason that I use any pre-built library: it makes my life easier.
sqlean's existence provides the kernel around which other things in the ecosystem can coalesce. For example, karlb's sqlite-sqlean pip module [1], which makes it easy to get these extensions in any Python project in a cross-platform manner.
I've used the math library myself recently: the SQLite in my distro is 3.31. I could install the tooling necessary to build a new SQLite, or I could use this project.
I also use the crypto library in my datasette-ui-extras library, which can run on a variety of end-user platforms. It's nice not to have think about the packaging myself.
To each their own, of course! But for me, calling this "mostly noise" is a disservice to its maintainers.
I don't expect anyone to use all the incubator extensions (like the cube root you mentioned). They are in the incubator and not in the main set for a reason.
Even the main set extensions are split into modules, rather than released as a single binary - so people can use them independently.
As for 'noise'. Well, good luck implementing `regexp_substr` and `regexp_replace` using the well-maintained and tested sqlite codebase. Or streaming file I/O.
It can be surprising difficult to upgrade to a more recent SQLite release, depending on your operating system and which language bindings you are using.
I still haven't found a good, reliable method of upgrading the SQLite version that is made available to Python's "sqlite3" standard library module for example, that works reliably across Linux and macOS. https://til.simonwillison.net/sqlite/ld-preload is one mechanism I've explored, but it's not ideal.
As such, extensions which package stuff that you could get in SQLite core if you had a good way of recompiling that with extra options are really useful.
Adding this collection as a project dependency would be opposite of "lean". Better to manually collect the functions you need, favoring the well maintained and tested sqlite code base over other sources.