Found this comment mentioning the ratings of IOTNBO. A nice perspective from a korean. :)
“I think I have to explain this as a Korean. While ratings are definitely important it isn't the only denominator that decides a show is successful or not in Korea even before the Netflix age. Korea has a huge generation gap and the artistic taste between the old and the young is drastically different. But it is usually the younger generation that spends more money so the advertisements usually target this demographic. However younger generation don't watch the show on air as much as their counterparts.(Or Korean contents in general) They usually hear about it later and decides to watch it or not. So the overall reputation of the show is also very important. Because of this nature we even have a term that is separated to ratings to evaluate a shows success. Which is '화제성' and '화제성' usually is measured by how often the show is discussed in the internet. I thought I had to say this because I have seen many comments about IONTBO not being popular in Korea because of the low ratings but this is one of those typical shows that is low in ratings and big in '화제성'.”
Translation of naver tv comments about episode 12 are here. :))https://k-communities.com/2020/07/27/k-netizens-reactions-to-its-okay-to-not-be-okay-episode-12/
My fave comment. XD
[+712,-2]Writer-nim, I really wanna see Kang Tae and Moon Young have a baby and live happily, please……
I just finished it. The episode made me happy and sad. I was happy about the ending but the preview made me sad again. :(( I also cried when Sang Tae comforted the other patient like Kang Tae did for him. (´༎ຶོρ༎ຶོ`)
1 
_(:3 」∠)_
https://twitter.com/rnjojoanna/status/1287628079938940928?s=21
“I think I have to explain this as a Korean. While ratings are definitely important it isn't the only denominator that decides a show is successful or not in Korea even before the Netflix age. Korea has a huge generation gap and the artistic taste between the old and the young is drastically different. But it is usually the younger generation that spends more money so the advertisements usually target this demographic. However younger generation don't watch the show on air as much as their counterparts.(Or Korean contents in general) They usually hear about it later and decides to watch it or not. So the overall reputation of the show is also very important. Because of this nature we even have a term that is separated to ratings to evaluate a shows success. Which is '화제성' and '화제성' usually is measured by how often the show is discussed in the internet. I thought I had to say this because I have seen many comments about IONTBO not being popular in Korea because of the low ratings but this is one of those typical shows that is low in ratings and big in '화제성'.”
source: https://www.reddit.com/r/KDRAMA/comments/hynge4/viewership_is_not_everything_kdramas_find/fze65pj/?utm_source=share&utm_medium=ios_app&utm_name=iossmf
[+712,-2]Writer-nim, I really wanna see Kang Tae and Moon Young have a baby and live happily, please……
https://k-communities.com/2020/07/27/k-netizens-reactions-to-its-okay-to-not-be-okay-episode-12/
( ͡° ͜ʖ ͡°)
https://k-communities.com/2020/07/26/k-netizens-reactions-to-its-okay-to-not-be-okay-episode-11/