There's a pretty strong culture of "no static linking because I need to replace the .so to preserve my freedom hurr durr" in a lot of Linux spaces, so quite a few of these C/C++ FOSS libraries are a pain in the ass to statically link.
Literally last week I was porting something to Linux and had to rewrite the libwayland build scripts because they only expose a shared object.
There's also an expectation that you're going to install them via your system's package manager, not build them, so a lot of them use insane build systems (autotools, meson).
You are right that there are many of us who prefer the package manager, there are so many reasons why a package manager makes your life wonderful. Debian has always been a proponent of dynamic linking. When you create a Linux distribution that is a big plus.
For me install size matters and statically linked stuff are too big sometimes. Of course a 100MB go statically compiled binary has huge advantages now days.