Had to do quite a bit of work to get filesizes down to something reasonable for:
http://shapeoko.github.io/Docs/
One late development was working up a mechanism where an image could be clicked on to open it in a new window:
http://shapeoko.github.io/Docs/content/tPictures/PS20028-100...
and then the part names in the parts list could be clicked on to highlight the matching part in the diagram.
For complicated shapes/curves I'll sometimes run it through an online editor to help visualize, this is a good one: https://yqnn.github.io/svg-path-editor/
Unlike Illustrator/Sketch/Inkscape it can also create and manipulate SVG animation elements (https://boxy-svg.com/blog/21) - a very powerful feature which is now supported by all major browsers.
It seems like a fairly straightforward mapping of UI -> SVG features, which must have taken a ton of effort. I'll have to take a closer look at the animation tool, I've often wondered if web technologies would ever get close to Flash's capabilities.
For something like this bell example (https://svg-tutorial.com/svg/bell), you can certainly hand-code it if you're really math-inclined and can estimate the formulas of curves just by looking at them, but for us mere mortals, it's easier to just draw out the curves in a graphics app (like https://youtu.be/5x2uHUB_pzw?si=fSLjRKlZNgVKVcOx&t=123 for Figma) then export as an SVG. And for things like the ringer (is that what you call it? the orange ball thing at the bottom of the bell that strikes the bell to make the sound), being able to visually draw it on a canvas, change its size, drag it around and play with its colors and dimensions, etc. is really helpful. Figma is fine for simpler graphics, but it's really more of a UX tool than a graphic design tool, and Illustrator is a lot more powerful. Inkscape is a FOSS option.
In other circumstances, though, manipulating the SVG XML directly is also very helpful. Let's say you want to programatically generate a bar chart. If you have a big dataset, it's going to take a designer forever to manually plot them and change them every time the data changes. But it's easy for a dev to use Javascript (or any language) to draw each rectangle, programmatically adjust their heights and colors based on the data, add tooltips, etc. And that way you can dynamically update them in real-time whenever the data changes (like if the user selects a different date range, or new events come in). A lot of this is made easier by libs like https://frappe.io/charts or https://apexcharts.com. But before you take that approach, you should know that for complex charts, sometimes Canvas rendering (or just generating graphics in the backend) can be more performant than SVG.
SVGs can also be animated and interactive, not just with CSS transitions but by directly manipulating the XML geometries, like http://snapsvg.io/demos/ or https://www.svgator.com/ or https://codepen.io/collection/XpwMLO/. This is fine for product pages and such, but for really graphics-intensive apps (full games) it's probably slower than other rendering pipelines. (Not my specialty, won't speculate too much.)
TLDR Drawing them in a graphics app is usually easier for the designers, but the XML can be programmatically manipulated afterward to great effect. The ideal workflow depends on what you're trying to accomplish, and also who you have on your team.
The "clapper".
I am still on the steep end of the SVG learning curve, but also generally start in Illustrator and then export, clean up, and hand-code the details.