It's the eternal debate. What has more impact? Employees joining the company and making changes from the inside? You always have the risk of having the employer be: "see! no need to change! there's no problem, people are still applying and we are filling all our position easily!"

Or the employer realizing they can't hire anyone good anymore and decide to make real changes in order to be able to attract the right talent?

It's hard to say which one has the most impact. At the end of the day, management needs to be on board to make changes