That percentage is actually pretty close to correct. For that reason and user studies of regular users Edge has already turned off their DevTools by default ( https://blogs.windows.com/msedgedev/2016/11/22/balancing-use... ).
Firefox is currently pursuing moving the DevTools out of the browser and will likely use a similar system to Edge / Safari for activating them. Going the extension route does have complexity drawbacks but being able to ship fixes faster, to a wider audience will be a greater benefit. Additionally as all browsers adopt WebExtensions this could mean that any Firefox panel developed as a WebExtension will be available for use within Chrome or Edge.