Microsoft’s back office suite is massive. So you’re talking about Nginx + a CMS + online office suite + video conferencing + identity providers and so on and so forth.
There isn’t really a direct comparison in the FOSS world. It’s either smaller in scope or smaller in terms of high profile organisation adoption.
This is why I think it’s easier to ignore the “Linux” part. Not because Linux is technically a kernel, but because there isn’t a directly comparable solution that targets Linux / GNU or whatever other base OS moniker you want to use. Same is true for BSD, Darwin and so on.
The alternatives to Microsoft’s dominance are typically more narrow in scope and usually proprietary too (eg Okta for identities, Google Docs for O365, etc)
Does this mean that Microsoft products are secure? Not really. It just means we cannot make a fair comparison against FOSS when it comes to these specific types of attacks.