If you’re looking to point, shoot, and share with the phone camera, and keep your mirrorless stuff true to life, you probably don’t need Photoshop. If you’re looking to create things that didn’t exist before, or bend reality, that’s where Photoshop would come in.

My dad is a big into photography and while he does his management and RAW processing in Lightroom, he still uses Photoshop here and there. He’s been enjoying playing with their AI image generation to change up scenes, replace skies, etc. Even without the AI, it can be good for tweaking things in the image to your liking, like removing a random person from the background of your vacation photo. Depending on what you’re looking to do, this can either be easy or take incredible skill.

Myself, I have a bit of an obsession with desktop wallpapers, and will often make my own or tweak ones I find to my liking. At different points in my life, going back 25 years, I’d use it for various things in school, work, or socially online. Not because it was required, but because I enjoyed it and could make things that didn’t exist.

These days I use Affinity’s suite instead of Adobe, so I don’t have to pay a subscription. Apple recently acquired Pixelmator, which I also used for a while, so I’m interested to see what comes of that.

The technical answer is layers and destructive edits, you could probably summarize this as compositing (i.e., combining different images together). I don't think there's necessarily even a correlation between pro vs. non-pro (I'm not remotely a pro, but run into limitations of the Lightroom-approach to editing [which is what you're talking about, editing that can't do destructive edits or non-adjustment layers] quickly). I think what it correlates with is whether you want to quickly edit lots of photos (Lightroom) or deeply edit a single photo without limitations (Photoshop).