The new Plus category of Chromebooks is an assurance that you’ll get a higher level of performance and features but still at a reasonable starting price.
With Chromebook Plus, you’re guaranteed to get at least the following specs, with a starting price of $399:
- 12th-gen Intel Core i3 or AMD Ryzen 3 7000 processor or better
- 8GB or more of memory
- 128GB or more of storage
- 1080p-resolution IPS LCD or better
- 1080p webcam with temporal noise reduction
This is an apples to oranges (or OS to hardware) comparison.
Lots of GNU/Linux distros have been receiving updates for decades now, although major releases do sometimes drop support for some hardware (typically an entire CPU architecture).
I don’t think ChromeOS is saying they’ll provide security updates for a 10 year old OS release (though maybe they are? but that wouldn’t be very attractive to most people), rather they’re saying “ChromeOS devices receive 10 years of updates.**” (with the ** being “For devices prior to 2021 that will receive extended updates, some features and services might not be supported.”)
And of course, yes, many other distros current releases today do have excellent support for hardware that is a lot more than 10 years old.