WebKitGTK benefits from sharing a codebase with WebKit for iOS, which web developers do care about supporting. There can still be bugs in the Linux-specific platform integration code, but that's not most of the codebase, so any given app is less likely to run across a bug in it. It's not as reliable as more mainstream browser-OS combinations, but saying that most apps don't work is an exaggeration.
Last I checked, WebkitGTK does not have parity with WebKit on iOS, and plenty of devs do test on that platform anyway - so I'm not sure what you're talking about? You're right to correct someone saying _most_ apps don't work, but it's also not cool to just sweep the WebkitGTK issue under the rug and pretend it's not an issue at all. It's bitten plenty of people who build on Tauri.
Additionally, the issues people find with WebkitGTK/Tauri aren't always web related, usually moreso Linux related (weird blank screens, issues with rendering certain stacked items, etc).