This is done to optimize for computer display. Also makes each discrete zoom level 2x of the previous one, and makes nice square map tiles.

Other projections are possible but end up with wierd map tiles, defeating smooth scroll on the draggable map.

https://venturebeat.com/technology/google-maps-is-now-a-glob...

All of the mapping apps are rooted in paper maps. That’s what most people find accessible in a natural way.

So, in any 2D world view some projection must be chosen, and you can fundamentally chose between true angles or true size. Because of that choice any projection is a distortion. Choosing true angles has advantages when it comes to turning projected data into something like turn instructions in your nav app. And then again, mercator projection is easy to use. So, bottom line it’s a mix of people are used to it and simplicity of using it.