To me, modern UI isn’t getting out of the way, it’s often asserting itself over the content it claims to get out of the way of.

The whole narrative here is bogus. Going back to when UI was more visually separated from something like your photos, that puts the focus on the photos, because it differentiates the content area from the UI. Whereas now, it conflates the two. When you blend, blur, and remove the line that separates them, it doesn’t make it more clear. It makes it far fuzzier. It literally is covering up the content.

I’ve Got Better Things To Do Than This, and Yet

You should go read the whole post. It's a tirade against the current UX trend of lip service to "get out of the way of content." During my tenure at Chrome, I remember a particular conversations with a delightful UX designer. I will admit that I was beguiled by the whole all-in-service-of-the-content and was pushing for a visual design change early on in the mobile days for the playback controls to be on top of the media player instead of its own bar like we started with.

I remember them using a phrase that really stuck with me - it's not getting out of the way. It's more about highlighting the content. So, it's content over chrome. In other words, it's the attention that one pays to the content versus the chrome. The thing about some of Liquid Glass choices is that you are (almost purposefully) designing chrome to steal attention away from the content. Or at least it's in strong contention with the content despite "moving out of the way."

It should never have been in the way to begin with. That is courageous design.