There is no native...modern developers be modern innit
Even on Windows:
* Windows Setup uses EdgeHTML, WinForms and UWP (as the OOBE process is a clusterfsck)
* The desktop environment uses a mix of EdgeHTML, Chromium, WinForms and UWP
* Edge uses Skia+Chromium
* OneDrive uses Qt
* Teams uses Electron
With exception to Teams, the above stuff ships as part of the base system these days and there's no escaping this mess because even in World Of Fruit, a ton of cross-platform frameworks are used for common third party apps. Gone are the days where people wrote cleverly abstracted backend functionality and paired it with separate UI implementations for each system.
GTK folks don't care about backwards compatibility between major versions, Qt folks don't care about long-term support, UWP is a dying fad and HTML-as-a-UI (ala Electron) is stupid.
What damage can Flutter do to Linux distros that everything else hasn't done already?
How is said damage any different to that occurring on other systems?