I assume that Google's takeaway from the Internet Explorer anti-trust case was that they needed plausible deniability for their non-standard browser features.
This was not a "Google" thing - vendor prefixes were a common practice in the industry. Webkit was using -webkit- prefix before Google was using it.
Many years ago the harm of this was recognised and browsers did move these to configuration/feature flags instead.
https://developer.mozilla.org/en-US/docs/Glossary/Vendor_Pre...
Apple, Mozilla, Microsoft, and Opera all were doing that before Google even had a browser; there never even was a Chrome-specific prefix, all of the features included in Chrome this way were -webkit- prefix and, IIRC, implemented in the WebKit shared codebase.
-ms- wasn't really a thing until IE10 if I remember correctly, when they started prefixing their own IE5-era properties like the DirectX-based `filter` [citation needed]