Microsoft does credit the authors on their README. Maybe it's not exactly the right way to do it, but they do it.
Now if it's not the right way to do it, what about opening a PR and asking to change it? Instead of writing a blog post to complain about them?
Now maybe those engineers thought they did well, will get issues internally because of the bad publicity for Microsoft, and next time they want to use an open source project their legal department will be even more of a pain in the ass because if they aren't, then random people on the Internet use that to do bad publicity for the company.
Why not assuming that they are in good faith here? There are enough reasons to hate Microsoft other than this one.
The question is who does the copyright belong to in this repository. It is both original author and Microsoft (because they took authors code and modified it). So the License file should mention both.
I am not convinced that the main LICENSE file should mention both. I feel like somewhere, in the project, there should be a copy of the original license.
When you depend on a third-party, you don't add their copyright in your main LICENSE file.
In case of deps, the dependency comes with its own LICENSE file.
In this case the code is essentially forked, integrated and intermingled, so that is why it should be in the LICENSE file.
If it was file or two, it would be fine to add a comment pointing to the license file in the repo, if it was a directory, or to copy it verbatim to that file. It all the copied code was in a directory then having it in directory would be fine.
In this case it looks like they took the original code and heavily modified it, so the simplest way to solve it is one LICENSE with both notices.
I don't read anything suggesting that in the MIT licence. I don't see why they couldn't say "the fork came with its own LICENSE file, which we moved in this subfolder, and now the root LICENSE file is the one of our new project".
The question is, "If I look at this repo, who owns the copyright?"
Sure, you could move the original LICENSE into a directory. Still, if the files are intermingled, you should have a prominent notice that says, " Hey, these files have mixed copyright ownership."
Now if it's not the right way to do it, what about opening a PR and asking to change it? Instead of writing a blog post to complain about them?
Now maybe those engineers thought they did well, will get issues internally because of the bad publicity for Microsoft, and next time they want to use an open source project their legal department will be even more of a pain in the ass because if they aren't, then random people on the Internet use that to do bad publicity for the company.
Why not assuming that they are in good faith here? There are enough reasons to hate Microsoft other than this one.