[dragonwriter]

> Almost all states are at-will. So severance isn’t required.

The former doesn't imply the latter; all (not almost all) US states have at-will employment, but that just means good cause is, by default (i.e., absent specific contract terms), not needed to sever an employment relationship; some states, and the federal government, nevertheless require notice or payment in lieu of notice and for some states additional post-layoff benefits (e.g., paying continued health benefits for a certain period) for certain large layoffs.