My recollection from previous OIN threads was that it came with a lot of caveats. I can't comment any further from lack of knowledge about patents and its subtleties. Would love to see an analysis of what really happened in practice since they did that.
https://www.zdnet.com/article/microsoft-open-sources-its-ent...
Apple had "1,996 total patents granted between July 1, 2019 and June 1, 2020, more than any other company in Silicon Valley."
https://www.bizjournals.com/sanjose/news/2020/07/27/top-of-t...