You may have to rephrase the question to what Microsoft is having on/for managers that make them keep sucking up to Microsoft. So much that people are forced to use their crapware.
> Why people still use those spying, ad serving services and then complain about it is beyond me.
Because they don't pay for services. Microsoft and Google both provide a paid version that is ad-free. Regardless of the version, neither use your emails for ad-serving or "spying".
There are plenty of things we should be critical about w.r.t Microsoft and Google, but this ain't it.
"The process of selecting and showing personalized ads in Gmail is fully automated. These ads are shown to you based on your online activity while you're signed into Google. We will not scan or read your Gmail messages to show you ads" [1]. This was apparently changed in 2017 [2].
GDPR, LGDP and equivalent laws plus the tangibility of emails (instead of the relatively-nebulous web history which Google could simply blame on "we only know what website we're serving from, we don't track you"). I don't know if US residents still get targeted ads using mail data though.