Great read, Jonathan! Couldn't agree more that we should all be kind and gracious with how we deliver feedback anyone, especially to jr designers. I'd challenge the notion just a bit that the "which UI is better" posts are innocuous and have any intention of garnering feedback from sr designers. I've often read respectful comments from seasoned designers met with defensive replies from the poster. These kinds of viral posts enjoy thousands of likes and re-posts, which I find to be harmful to our industry as well as the designers themselves for future employment.
When I'm interviewing younger designers, I'll look over their public socials to see what kinds (if any) industry posts they make. Are they hungry to learn/grow? I sometimes see the opposite, a bit of perhaps well-intentioned, but cringey "right/wrong" or "which is better" posts. This is red flag for me.
I think our industry as a whole has a real issue with hubris from both sr and jr designers. It's more evident, however, when I see it in social posts from inexperienced designers. All this said, I think you nailed it with how we speak to each. Thanks for writing this post, I enjoyed reading!