I have noticed that on a freshly installed system with both Kate and LibreOffice installed, Kate wants to be the default program for .rtf (rich text format) documents. While it is possible to open an .rtf file in a text editor to edit the raw formatting codes, that is not a common use case for opening an .rtf file. It really should prefer LibreOffice over Kate for this file type.
I don’t have kate installed, I’m on Fedora 42 so I just created an *.rtf file in LibreOffice and saved it and opened it again and it launched kwrite rather than LibreOffice. Easy enough to change the application order preference under the files properties. But I agree with you, it should have LibreOffice at the top of that order for *.rtf files.
However I suspect that has something to do with each individual distro and how they package KDE and whether or not they include LibreOffice by default. So something needs to be set to open *.rtf files, and every distro, even if it doesn’t have an office suite, should at least have a text editor.