I've done frontend since IE6 was the major browser. Back then most of the time was spent using hacks to work around the limitations. No rounded corners, no opacity, no grid, etc. As it got easier, with better adoption of the web standards and better tooling, frontend-devs were able to do more. But I feel as REST and GraphQL got more adopted a lot of the complexity moved from the backend to the frontend. The frontend part is easy these days, but working with the backend is the hardest part of being a frontend developer.