When you want to layoff a large number of people: RTO will increase the number of employees quitting so you don't have to layoff as many
When starting a company: WFH means you don't need offices, or at least smaller offices which makes a big difference
When you do a hiring push: being open to WFH gives you a bigger pool to draw from
Onboarding a large number of new WFH employees at the same might easily turn into a disaster though (for example if you "need" to grow your headcount at 50-100% per year like Unity did... of course they didn't need to do that but that's different problem).
Depends on the job market in that area.
People only quit if they know they'll easily find equal or better paid gigs than what they already have, but in 2023 most people working in tech tended to stay where they are due to the market stagnation/slump, especially if they got above market rates during the 2021-2022 boom and know they won't get anything better in the current market.
I don't think this is true (or at least, it has tons of exceptions). People quit if they think that they have an alternative that is better. This doesn't have to mean equal or better pay. I know a number of people who have quit and taken lower-paying work because those jobs improved their quality of life in other ways.
When you need to start a company or do a hiring push, being in an office can help.
In a company that only hires high seniority employees, WFH vs office doesn't matter much.