Adam,
I heard you don’t find sharing that useful. Is that just for the Mac or even iOS. I use it all the time in iOS and is an integral part of my workflow. On the Mac, I use it to forward web sites to Mail, but also grab recipes with Paprika and put text and clippings into Notes.
Do other people have other uses for the sharing that they use regularly? I do find that it is not intuitive to find a use, and people may not know they can use it if it is not checked and “on”
Hmm, interesting question. On the Mac, I never even think to use the Share button and I’m honestly not sure if there’s anything it would do for me. My guess is that the main things I’d want to share are URLs to Web pages, but there’s almost no win in choosing File > Share > Messages and addressing a new conversation instead of just copying the URL and pasting it into the appropriate conversation. Plus, because I need to embed URLs in my writing all the time, I’m really, really fast at switching to Chrome (F3), selecting the URL field (Cmd-L) and copying (Cmd-C) and then switching back to wherever I was (Cmd-Tab or another F-key) and pasting with Cmd-V.
In iOS, I do use the Share sheet, but largely for the Copy button in a Web browser because copying from the address field isn’t reliable. For Paprika, I use its internal browser, so there’s no need to share from Safari or another browser. I don’t particularly like or use Notes, but I’m playing with using it to collect ideas for a summer trip we’re taking, and I should try using the Share sheet approach instead of trying to drag from one side of split-screen view to another, which is flaky when Chrome is the browser (and I need to use Chrome because of its automatic translation of Web sites that are in French or German).
I don’t use it much on macOS, and on iOS I (like @ace) use it mostly for copying URLs.
But, I find I’m suddenly using it much more on both OSs to save items to Keep It. Keep It is the successor to Together (which was the successor, apparently, to Keep It Together, which I never saw). It’s dramatically improved compared to Together — and I’d strongly recommend trying it for gathering vacation info.
I’m using it about 2/3 for saving (and searching) academic articles as PDFs and about 1/3 for my own notes, thoughts, outlines, gift lists, and the like (all in Markdown). It’s also really good at storing web pages (either as URLs, web archives, or PDFs).
So all of a sudden the Share button has gotten a lot more useful for me, anyway…
I use the Twitterrific MacOS extension frequently as it allows me to select a sentence of text and send that directly to Twitter, with the URL.
And perhaps sometimes I do use the Sharing icon to email a page if I’m feeling too attached to my coffee cup to put it down and use the keyboard shortcut to email (Shift + ⌘+ i ), which requires two hands to comfortably trigger.
I use Share often on the Mac side as well. When I share links, often the person I want is already there in the drop down.
I use it all the time to share photos and documents.
Funny that Adam mentioned F3 - I just tried it and it’s not working for me, though it seems to work fine when a cat steps on the keyboard.
Diane
I map all my F-keys to particular apps with Keyboard Maestro, so no one else will have the same mappings. 
Funny, because now it’s opening Mission Control!
Diane
That’s probably the default keyboard shortcut in System Preferences > Keyboard > Shortcuts > Mission Control.
I use Share all the time. Both OS’s. But if I’m in Safari, I’m hard-wired at this point to hit Cmd+L to select all in the address bar, that I do directly.