Pre-Safe occupant protection including pretensioning reduced stress to the head and neck by 30-40%: https://media.daimler.com/marsMediaSite/en/instance/ko/The-P...
The comment is about safety, not just luxury, and Mercedes has been on the cutting edge for over a century. You can read about their list of innovations including being the first to have crumple zones, airbags, anti-lock brakes, traction control, and more: https://www.mbusa.com/mercedes/benz/safety
> "and some cars in the 90s had a feature that would put the whole seatbelt on for you"
Are you referring to the belts attached to the A-pillar that would slide up when you sit? Those didn't handle the lap portion and were proven terrible by safety testing and consumer response.
The pre-safe sound linked here is another example.
Citation needed. The little seatbelt tightening thing is cute but probably doesn't increase safety at all, and some cars in the 90s had a feature that would put the whole seatbelt on for you.