I think the big motivation is now "embedding", i.e. using servo as replacement for webview/cef/etc. So for example you could think Tauri+Servo as Rusts answer to Nodejs+Chromium in Electron.

https://servo.org/blog/2024/01/19/embedding-update/

Another example would be Qt which normally uses Chromium for webviews but now there has been work to use Servo instead: https://www.kdab.com/embedding-servo-in-qt/

Mozilla didn't "scrap" it (it was an open source project from the start, so they coulnd't have scrapped the project even if they wanted to), but they laid off the Servo developers in 2020. The project moved to the Linux Foundation and then apparently languished for several years, but at the end of 2022 (https://servo.org/blog/2023/01/16/servo-2023/) it was picked up by Igalia, and since then it has made considerable progress again. This presentation has a lot of details: https://servo.org/slides/2024-04-16-seattle-rust-user-group/

To develop the engine?

> Servo is a web rendering engine written in Rust, with WebGL and WebGPU support, and adaptable to desktop, mobile, and embedded applications.