Almost everything you need to create vector art, SVG doesn't support.
Multiple outlines in a single shape? No. Varying thickness in an outline? No. Rounded corners on arbitrary vertices? No. Non-destructive boolean operations? No. I'm not even sure SVG supports paragraphs.
Many of these Inkscape implements as live filters, which are saved as SVG extensions in the XML .svg file that nobody but Inkscape can properly load.
SVG is ridiculously bad as a creation format. It's a good format to export to, but as a backend and it's just insane. It's like using a single PNG file as a backend for your multi-layer 128bpp raster project.
I use Inkscape a lot but I can't help but notice that the best vector art illustration come from Affinity Designer, Corel Draw, and Adobe Illustrator. If you compare the quality of artwork made with proprietary tools to those made with Inkscape, it's very clear that Inkscape severely limits what artists can achieve. You can easily create complex illustrations in other tools that would be a nightmare to manage in Inkscape. Just compare how you clip something in Inkscape to how you do it in Affinity. It's ridiculous how different the two workflows are.
I also used CorelDraw for many years before moving on to Inkscape, and there were definitely some features that I still miss (e.g. better power clip behavior, blend shapes, etc). But I have came to appreciate Inkscape using SVGs because it allowed me to build my own tooling around it, I only needed libraries that can read and write XML.
SVG is maybe not the best format and Inkscape has many extensions that made their SVGs nonstandard (e.g. mesh gradient), but it is a fairly accessible format. I am not sure the gains promised by a proprietary format would be worth losing out on various SVG/XML tools.