Oh, yes, none of it is sandboxed from an actively malicious app—but an actively malicious app can just ignore your hosts file, too.

My threat model is a developer who includes a standard tracking snippet from a third party but is not going out of their way to reliably violate my privacy at all costs (because they have other features to ship, and the tracking snippet works on most computers). If your threat model includes actively malicious developers, stop running native apps from them at all.