Well, earlier Google was accessed via desktops by people looking for information or answers. But now, people use Google over a wide variety of platforms, apps and devices for a wide variety of reasons. They access Google through mobile phones, TVs, watches, and, yes, sometimes a desktop too.
The initial Google logo was developed for a single desktop browser page. It has now been updated for a world of seamless computing across an endless number of devices and different kinds of inputs such as tap, type and talk.