But yes, SVG is extremely bloated and under-documented. Especially SVG 2. The core resvg codebase is close to 20 KLOC, while the whole package is like 50 KLOC.
On the other hand, resvg is an exception, because it doesn't rely on any system and/or 3rd party libraries. 95% of the code in the final binary was written by one person (me). Not because it was strictly required, but because it was fun. resvg is basically an epitome of RIIR.