The number 1 use of WebGL is Google Maps by several orders of magnitude over any other use. At some point they'll likely switch to WebGPU making it the number 1 use of Google Maps. Google went over what this enables when they shipped it. Lots of features including being able to highlight relevant roads that change depending on what you searched for.

https://www.youtube.com/watch?v=HrLyZ24UcRE

Apple maps and others also use it