If they did that all the USP that exists in Firefox would be gone and their market share would fall to 0.001% instead of 3%. People might praise Microsoft for

If they did that all the USP that exists in Firefox would be gone and their market share would fall to 0.001% instead of 3%. People might praise Microsoft for moving Edge to Chromium but ultimately it's because Microsoft couldn't compete on web standards and security and didn't want to invest further resources in to something not earning them money.