You could say the same for every "open source" products backed by a Multi Billion dollars corp, React (Facebook), Go (Google), ... Java (Oracle).
> This kills the business model of InteliJ which does a lot of work in making great IDEs
I don't think so, PHPStorm is still miles aways in front of VSCode for PHP development, and there is no serious Java dev with VSCode either. Jetbrains will be OK.
> Think about it for a moment: this kind of open source kills genuine businesses due to the monopoly position of the company “sponsoring” it.
VSCode became popular because it learned from the philosophy of Textmate and Sublime Text: A good IDE should be first and foremost and excellent text editor. If anything VSCode "killed" Atom, but both belong to the same corporation.
Now yes, Microsoft is getting unpaid developers working on their product. There is certainly a moral angle, but it's not really killing the paid competition.
If anything they complement each other as no one would accuse intellij of been quick to start often I'll whip into vscode for those edits.