The article states that the expert thinks it's a problem in Korea and Italy, too. I can't speak for Italy as I've never been there, but it is definitely not common in Korea. Yes, Koreans live with their parents until they're married, typically, and yes, some Korean males are kind of shut-ins, but it's definitely not a phenomenon here like it is with our neighbors across the East Sea.
I can't say for certain what caused the differences between Japan and Korea despite the countries have very similar cultural and historical backgrounds, including economically, but for whatever reason that's kind of unheard of here.
I agree, I'm definitely familiar with 20-something relatives having trouble entering the workforce in Korea, but I've never heard of this particular phenomenon there. I've heard of different issues, like PC bbang/gaming addictions and the occasional shut-ins.
It feels like all the pieces are in place for a Hikikomori-like phenomenon to hit in Korea, but somehow conditions are just different enough it doesn't happen. It might be that the cultural pressures to get a job and get married (and get out of the house) are just ever so slightly stronger. It also doesn't hurt that it seems more socially acceptable to seek employment outside of salarymanship to Chaebol. Sometimes I think it seems like every person in Korea has tried to start their own business at least once.
I can't say for certain what caused the differences between Japan and Korea despite the countries have very similar cultural and historical backgrounds, including economically, but for whatever reason that's kind of unheard of here.