Tauri does not do this in all cases, as WebkitGTK on Linux has performance issues and is often the ugly duckling of everything.
I also feel like I will have to, yet again, trot out the comment from a Slack dev that explains why they moved _from_ per-platform webviews to Chromium. This isn't new ground being charted, plenty of companies and teams have been down this path and Electron exists for a reason.
(I am not saying Electron is _good_, I am saying that Tauri isn't the holy grail people make it out to be)
According to https://slack.engineering/building-hybrid-applications-with-..., Slack never used multiple different per-platform webviews. The earliest version of their desktop app was Mac-only and used the OS-native WebView API, but they switched to Electron at the same time they started work on making the app cross-platform. At the time, not only did Tauri not exist, but neither did the WebView2 API that it uses under the hood on Windows; they would have had to use the WebBrowser ActiveX control, which uses Internet Explorer's Trident engine and was already deprecated. So it's not so much that they rejected per-platform webviews, as that per-platform webviews were not yet really available as an option on desktop.
Isn't Spotify using CEF (Chromium Embedded Framework) rather than Electron?
Regardless, your point stands: it's a bundled Chromium on all platforms
https://news.ycombinator.com/item?id=18763449
It took me 2 seconds to find in Google, and you're splitting hairs if you think it being macOS-only was the point of my comment. Their second bullet point is just as true today as it was back then.