The issue people are talking about unemployment rate and not the joblessness rate is that people care about ability to get a job if you want one. The joblessness rate includes people who are looking for job but can’t get any, but also people who are supported by their spouses, retirees, and people living on government benefits who are not looking for job, because they are disabled, too busy with childcare, or care for other people needing it, or ultimately too lazy and having too little self-respect to stop living on charity of others.
This wide aggregation makes it very difficult to understand what actually causes changes in it: are more people jobless because of expansion of disability benefits? Or maybe there was a surge of people retiring early? You need to look at other indicators to understand it. For example, good amount of growth of employment rate in recent years is a result of many people, who previously drew disability benefits to compensate them for their inability to work, actually going to work, once the work became better option than government check.
For this reason, unemployment rate is a better metric to look at, because it tells you something more useful and has better signal to noise ratio.