TUIs run on any OS with minor patches to support quirks, GUI frameworks need a lot of work. TUIs don't need to follow any OS guidelines, cross-platform GUIs always look bad outside of the "main" platform.

If you're only targeting macOS/Windows/Gnome/KDE then the solution is easy: just grab a GUI control set and go ham.

Then there's remote access: you can spawn an X11 app through X forwarding and have a terrible laggy experience on Linux, you can use RemoteApps on Windows to have a good remote experience (but almost no other platform), you can use VNC to have an awful cross-platform experience, or you can use a TUI and have all the graphs and interactivity you need over a responsive, low-bandwidth connection on any combination of client+server.