They are mostly talking about the "economically inactive"
A lot of these will not be claiming any benefits.
You cannot (or rather there is no point) cutting or sanctioning benefits that people are not getting.
For example, the headteacher at a school I worked at had a heart attack. His parents died during Covid and he inherited a lot of money. Technically he is still of working age... but he doesn't want a high stress job (doesn't want another heart attack) and is enjoying himself releasing albums until he's old enough for his pension.
He is economically inactive. Not claiming benefits. Could be doing a part time job.
Or a friend of my daughters who had a serious heart problem during Covid. It wasn't treated until a year or so later and now she lives with the impact of it. She's not well enough either to go to uni or to work full time. She lives with her parents - no benefits as her parents support her - and would like a part time job but would also like not to aggravate her heart condition and die.
She can't be sanctioned or her benefits cut because she doesn't get any. But she would like to work.
And there is fuck all support out there for people with physical or mental health problems to get them into work.
Jobcentres don't help people like this.