it's a few hundred lines worth of scripts to produce an ungoogled chromium with some nicer defaults, why wouldn't it, in case pointing that out is meant to be a criticism.
qutebrowser is not technically a "Python web browser". The GUI uses Python Qt bindings, and the browser engine itself is QtWebEngine. Python is simply the glue that ties it all together, and any language could be used instead, since performance is not a concern. This is why there are so many small niche "web browsers", such as Luakit, Nyxt, surf, etc.