Most purists insist on coding things in HTML/CSS and this stack is fairly unworkable for a good visual editor. Anyone who has built a robust visual editor ends up building one using canvas. (Figma is a great example)
Figma is great but it's not using classical tags to express fonts, tables, layout. Similarly Flash got it's layout and animation right... it just wasn't a web standard. A Canvas based editor/builder/WYSIWYG approach would be fantastic but it required us to move past HTML/CSS in the traditional and compatible model.
Said another way - if you try to use HTML/CSS to build a layout tool, you end up having to re-create browser layout and rendering engine.
Developers could build a design/tool similar to flash using canvas and I've actually prototyped elements of a tag/based design language that gets rid of the traditional HTML layout engine. It's significantly faster (1000x) to render/send over the wire but the moat of HTML/CSS is so large that I'm not sure there's interest in such approaches.
"Most purists insist on coding things in HTML/CSS" you write that like it's something bad.
Compared to flash HTML and CSS as enormous advantages ... it's not resource hungry and is accessible if you do it right. Through you have to know your art to use the advantages.
As a kid first learning about programming flash was amazing. The ability to draw or sequence sprites together into animations and then easily stitch those together into simple games is really powerful.
I'm not saying that we should bring back flash for entire websites as was trendy for a second, but I do think we lost something special that had a low barrier to entry for kids, artists etc to create interactive experiences
Ressource hungryness has changed since flash is no more.
Somewhere around half of the last decade, we starting having Chrome and Firefox taking hundred of megabytes per tabs and totalizing a few gigabytes that put them very close to what flash used to take, maybe cpu usage is still lower though.
It's not just that... It's pixels, em, ex, %, px, cm, mm, in, pt, pc... Not to mention margins, padding, box-model, absolute and relative positioning, flex-box, etc. etc. HTML/CSS is one of the most complex standards. You have to remove a lot before things get trivial.
Figma is great but it's not using classical tags to express fonts, tables, layout. Similarly Flash got it's layout and animation right... it just wasn't a web standard. A Canvas based editor/builder/WYSIWYG approach would be fantastic but it required us to move past HTML/CSS in the traditional and compatible model.
Said another way - if you try to use HTML/CSS to build a layout tool, you end up having to re-create browser layout and rendering engine.
Developers could build a design/tool similar to flash using canvas and I've actually prototyped elements of a tag/based design language that gets rid of the traditional HTML layout engine. It's significantly faster (1000x) to render/send over the wire but the moat of HTML/CSS is so large that I'm not sure there's interest in such approaches.