Interesting, and very useful, though I don't use Lightroom.
As a Linux user, I use XnView MP to manage my photos and Darktable for raw editing.
I chose XnView MP years ago, specifically because of the control it gave me over metadata. I can mass change captions, etc., for a set of jpgs. I can also preset simple edits and captions when I need a quick fix for blog posts.
Darktable allows metadata preset when loading a group of raw images, and creates the xmp file which carries the metadata into the final jpg. From there it's a matter of darg and drop to WP and everything is there.
Gutenberg, which I really like, also makes caption editing much more efficient.
The challenge which I haven't fully resolved yet, is captioning photos when I edit in Snapseed and upload directly from a mobile device.