> and most people reading HN (in fact, most people working at startups in general) are likely to be employed at-will

I'm not so sure about that. While Silicon Valley particularly, and the US in general, has a disproportionate number of high tech startups, you also have some of the weakest workers rights in the world, and while I don't know the exact demographics of HN, I'm not so sure it is that focused around California.

Pretty much all of Europe, with a population of about 800 million, for example, have protections that are vastly stronger. A substantial majority of countries have 1-3 months notice periods that are hard or impossible to get around, in some cases with a legal right to actually continue to show up to work and carry out the contracted work during that period even if your employer would like to pay you to stay away.