Do people use SVG?

SVG's are great, as the format has some unique properties: It's endlessly scalable! Being vector based, you can blow it up to any size without loosing resolution. You can style it with css! That's right, you can change stuff like fill and line colors with css! So you can also animate it with css! SVG's can be really light! Properly optimized an svg can be less than a kilobyte. It can be inlined! Instead of fetching it from the server as an image file, adding an extra Http request, the vector path can be inlined in your html, your css or even stored as a variable in javascript! This makes SVG's very suitable for icons in particular, but also for logos. Unlike gifs, PNGs and Jpegs, they scale very well and look just as good on a full-screen retina iMac as on a tiny lowres dumbphone. They're very good for things that change style and color, for instance a big colorful logo that Shrinks and sticks when you scroll down and maybe changes to monochrome - lots of cool effects are possible

Taken from: https://www.quora.com/When-should-I-use-SVG-instead-of-complex-HTML-CSS

TL;DR: SVG's are of utmost importance when it comes to logos, icons and general vectors. They are widely used and you'll likely see them on 99% of the websites you visit.