IDK. Defender had a good reputation when I still was on Windows, 8 years ago. It was non-intrusive and didn't slow down the OS like other AV solutions. One good experience I had was when I dragged a zipped e-mail attachment to the desktop out of interest and Defender immediately quarantined it. Don't understand the MS lingo in the text you quoted but yeah everything mentioning 365 sounds like a PITA. So maybe it's BS now.