How do mimeinfo.cache files relate to mimeapps.list?

The different mimeinfo.cache files are populated by update-desktop-database from the .desktop files you have around.

However, file browsers and such seem to use mimeapps.list files. Manipulating those can be arduous, in particular if some app was greedy and registered itself with many Mime types I don't want to see it on.

Ideally, one would change (or override) the .desktop files of the offending applications and the aggregated lists would be updated accordingly. How does one do that?

Copy the desktop file from /usr/share/applications/ to ~/.local/share/applications/ and modify as needed.

Just remove some entries in MimeType

...
MimeType=text/html;text/xml;application/xhtml+xml;
...

Afterwards restart session.