I would posit that most of your points are relevant for the economy as a whole, but you are missing inflation, which is probably the 2nd or 3rd most important factor for the economy as a whole (after your number 2 and your first number 3), but the single most important factor for tech workers, who are seeing huge comp increases due to stock packages in an M2 fueled bull market. That, and remote working trends, as you mentioned.

When you can get a 30% raise at a new job and there is too much psychological resistance for companies to give those raises internally, high turnover is inevitable.