The point is to spare the hassle of adding it as pre-built libs to a client project, as that involves extra variables regarding compatibility, and the management overhead and rigidity.
It's much easier to just add to the host's build sg. like an sz/lib.cc that just includes all the (not very many -- that's what enables this in the first place!) other code that would normally be separate translation units (i.e. not headers), and would be precompiled and assembled into sz.lib.
The main advantage of this is that it could still be shipped/integrated as source-only (but not "header-only") without its own opinionated build setup!
The point is to spare the hassle of adding it as pre-built libs to a client project, as that involves extra variables regarding compatibility, and the management overhead and rigidity.
It's much easier to just add to the host's build sg. like an
sz/lib.ccthat just includes all the (not very many -- that's what enables this in the first place!) other code that would normally be separate translation units (i.e. not headers), and would be precompiled and assembled into sz.lib.