The paid gtk devs refuse to accept patches to gtkfilechooserwidget.c (it's "frozen"), you'd know this if you yourself tried to make contributions to gtk. They owe us nothing, but the fact remains they have been removing features (like respecting the gsettings (org.gtk.Settings.FileChooser location-mode) that would allow users to fix this bug). And they refuse to fix it themselves or look at patches from others. I ask once per year. Even just 2 lines in gtk/gtk/gtkfilechooserwidget.c swapping in priv->location_mode = LOCATION_MODE_FILENAME_ENTRY; would help.
I'm a little confused whether your comment is the answer to mine or someone elses, cause we seem to agree on all points. In any case, I left G* lands ages ago (gtk2->3) and can only speak for that time. It coincided with the issues around their development policies.
The same bug exists in gtk4 too and they also refuse to fix it there. https://gitlab.gnome.org/GNOME/gtk/-/issues/5872
So, to conclude, everything you said is wrong re: this specific instance even if it may apply generally.