Nobody cares about 27in screens? You know it's all about distance? If you have a bigger screen yes you can sit further away but you're still within the same optimal view distance for the screens size as if you were sitting closer to a smaller screen. It's all a ratio.
Good posture means sitting up in your chair, butt all the way back, knees slightly below hips eyes should be level with about the top 1/3rd of the screen at a comfortable distance. Distance can be measured twice. The 1st time is moving away from the screen until the user can comfortably read, the 2nd is from the 1st distance move towards the screen until comfortable, the optimal distance is within those two comfort zones. Screen size doesn't matter.
Your back and neck must be killing you from all the ugly slouching or does your supremium gamer chair have anti-slouching tech? I find it hilarious you think spending fat cash on a "gamer chair" will suddenly make me like using a larger screen more even though I would have to sit back further to be at the same optimal view distance.
You had another terrible error.
"it is after all, it is"
You could have said "after all it is a third system" or "it is after all a third system" or even "it is a third system after all".
You are at a desk for 4h+ gaming and sitting upright, then it is because one is ignorant of ergonomic, or poor.
Smaller isn't better. Nobody want to stair at a TV monitor from 1 foot away... they are stuck doing it. Given unlimited cash, how would you design your computer room, wooden desk? Or would you take ergonomics and comfort along with human condition into consideration.
Please stop, you are embarrassing yourself here. There are studies for ergonomics and such... you sound like a kid in a basement, not someone who been building their computer room for 25 years. The whole point of building a computer desk and chair is so you don't have to slouch (like a kid in a college dorm), as with a proper set-up you play slightly reclined. I have an orbital keyboard tray that swings out to me... I don't have to lean into my monitor.
The mere fact you said screen size doesn't matter, it is all about ratio is hilarious. You assume every person want to be like a needy college student and sit with a monitor right in their face with a 24"?, or even closer yet with a 21". Obviously, the more you move it away to comfortable position, the bigger it has to be...
Tiny text @ 1440p on a tiny 27" is for tiny people with tiny wallets. It is not what you want, it is what you decided on given what is out there.