From what I've seen it's been getting much better. Linux has very powerful tools for media creation/editing now: Blender, Krita, Darktable, Natron are some quality apps that I'm aware of.

The problem is that they still pale compared to the Windows/Mac applications.

I'm not sure what toolkit Adobe use but I have a feeling it's not easily portable to Linux.

Inkscape and Gimp are the stalwarts, but for someone coming from Sketch or Photoshop they feel quite ancient and somewhat messy.

https://www.figma.com is cross-platform (web based), and a pretty good Sketch competitor

For a Lightroom replacement, Darktable is actually quite good (though I really miss the high quality shadows/highlights algorithm from ACR)

Check out Krita sometime as a Gimp alternative. It's geared toward digital painting a bit more, but it works for general image editing too.

I've played around with it a bit - someone packaged Krita as a snap for Ubuntu and I wanted to test installing it. Looked good, more for painting like you say but looked powerful enough for basic image editing. I've seen people produce beautiful digital art with it

That depends on what kind of creative pro you are. In general I'd completely agree with you, but the major VFX vendors all run on Linux - with Nuke, Maya, Houdini, Modo, Clarisse, Mari, etc.

If you get lucky with your particular combination of hardware and drivers, yes this can be true for some people.

I think you can forget Adobe porting all their stuff to Linux. They have a ton of different projects and teams going on at the same time, they certainly are not going to bother increasing that by 50% to support an open source platform with 1.x% market penetration.