> But vendoring may also mean you took the 2% of the library you need and not the 98% which reduces the surface area for vulnerabilities

If you aren't using a library function you're not vulnerable to exploits in that code: unused but imported code is inert (possible usable as a gadget if you're vulnerable elsewhere, but at that point you're screwed anyways) and most compilers/runtimes completely eliminate it.

> you may update a package that was previously good and is now vulnerable (regressions, supply chain attacks)

There are better mitigations to this than not using a library.

You still completely ignore the license violations.

You might be exposing it to attackers without intending to use it.

>You still completely ignore the license violations.

The ones that you are imagining to happen? Its not a problem because you could simply observe proper licensing.

>If you aren't using a library function you're not vulnerable to exploits in that code

Not true, just because you arent calling a function doesnt mean it cant run. Read up on Log4Shell.