Did you read the article you linked too? the retired, the sick, students, SAHM's make up the vast majority of these 9m people.
So who does that leave? they don't want to work, so they wont be on benefits, will be on their pensions and or savings.
Perhaps if the tories hadn't trashed the NHS and MH services, there would be less people off sick.
I ve worked in Job Centres, the long term unemployed are very often unemployable, they'll be looking for work but they have no skills that employers want and have no recent history of work.
e.g a young man down the street from me, is 26, never worked, MH issues (still on a 3 year waiting list for help) can't drive, is physically weak, zero drive or ambition - what can he do? he lives at home and receives about £80 per week UC, most of which his stressed out FT working mum gets.
If his benefits were stopped (as you want to do) he would have to leave home and go where? presumably you wouldn't house him, so he'd live on the streets, then what? drugs/crime/early death.....