> Why do vector images need a page?

I make slides on Inkscape and until now had to resort to clunky solutions to generate multipage PDF files.

> Do people print them?

Yes. People print PDFs.

> Mostly there is no pre-defined size. So the page dimensions are meaningless.

That’s not true if, for example, you need to render vector graphics on a screen. Since it’s physically impossible to show the entire Cartesian plane, you need to constrain it somehow.

Interesting, that sounds more like what people used to use desktop publishing software for. Is Inkscape even the right tool for that job? Doesn't sound like it's the core use case for it at least. But cool that it can do it. I'm obviously not a designer or a hard core user of any vector graphics tools. Frankly, Inkscape is a bit intimidating to me.

What I would expect is that you design maybe to have your graphics fit some area (box, circle, whatever), then you save, and then when you use the graphics (on a web page, in a presentation, etc.), you scale it to whatever desired dimensions. While you are editing, you zoom in and out as needed.

Screens are a good example actually. They have different dimensions, pixel densities, aspect ratios, etc. So web design tends to use relative units (em, rem, px, etc.). Also, is a screen a page? Or just a rectangle with some aspect ratio.

Take icons for example. Which is probably a core use case for Inkscape. You'd design some logo to fit square dimensions. And then you'd export bitmaps in various pixel sizes. Does that square have any meaningful dimensions? IMHO it doesn't. Certainly almost never actual paper sizes.

What baffles me as a rather casual user is that when I need to do some vector work for an icon (typically) and the first thing I'm confronted with is paper dimensions.