krita.org is a similarly polished and professional open source project, but I agree these types of projects are the exception rather than the rule (though I suppose the same could be said about most products).
It's an exceptional drawing tool that is well-suited for professional work and is headed in a really promising direction. It's got a couple of weaknesses (vector layers) but it really shouldn't be discounted as a professional-level tool.
Unless you're claiming that Inkscape is in the same position and has gotten a lot better than the last time I used it, which :shrug: could be true, I don't know. I'm not trying to bash Inkscape here.
So the workflow I end up using for digital inks is: Open both programs, sketch in Krita, copy-paste the vector data into Inkscape, stroke->path, then use tweak tool to sculpt the lines. This adds line weight in seconds-to-minutes. Alternately, I can apply path effects instead of stroke->path, if I want a more programmatic design. If I want to paint, I can copy-paste the shape back into Krita.
It did take me a week or two to adjust to Krita’s hotkeys coming from a lifetime of Photoshop, but the software in the end is leagues better for painting.