While I can appreciate your perspective, there are plenty of hard problems on the frontend. Many of them might fall outside the confines of the label frontend (into graphics programming or linear algebra), just like Google scale falls well outside what I'd call backend if we're sticking to a simple dichotomy.

Here are a few harder problems that I can think of:

- Draw a non-linear gradient along an arc with SVG

- Implement a constraint solver in JS

- Convert a CgBI image into a standard PNG with the browser File API

A good portion of the work I do on the frontend is transforming and composing data, and wrangling that data together from a multitude of different services. This honestly isn't that different from the work that I've done on the backend of the stack.

I'm not trying to discount how hard problems can be when they're distributed, just trying to point out that you can do interesting things in both domains.