As an IT person - I openly admit "Broken" IS a trigger word. I hate thinking that something I've built doesn't work correctly. It triggers me to Do My Job and fix the problem. And then, I Thank the person who pointed it out. Coding is a big messy world, things will break - people who report the errors are Helping you out! There's ZERO excuse for this bug being left uncorrected for so long. There are millions of people whose workflows involve having a window open in the background. It's not even a topic worth debating. Someone at MS is being lazy and/or living in denial about their own work/skills/abilities. Just get over it and fix it. Do your job.
Thank you.
I would also reject the suggestion that a viable workaround is to ensure File Explorer is closed... if you were to navigate to a folder using File Explorer and open a Word document in that folder by double-clicking it, File Explorer would remain open and the Word document would now be in the foreground.
It would be a pain to then manually close File Explorer to avoid this bug.