Personally, it would make flashing ESPHome devices much more convenient. Not having to switch browser for a start. The ability to plug a board into whatever PC on my LAN and just flash it, without having to install and maintain the entire toolchain is nice as well.
More broadly, there are web based IDEs for microcontrollers. Arduino has one: https://docs.arduino.cc/learn/starting-guide/the-arduino-web...
A few of these are aimed at the education sector, removing a some of the significant barriers faced by educators that would otherwise have trouble getting the software installed and keeping it updated.
In one of the discussions, someone was using it to help dental offices retrieve data from some specialised hardware. Browser support dealt with similar concerns of how to distribute the software to non-technical clients and keep it up to date. It was also something their clients understood, rather than something new.