The players will know what's going on at all times. And with technology these days so will the fans (even taking into account the dodgy signal at the CBS).
I'm pretty sure you aren't allowed to have the whole ground sold out to season ticket holders in England. There also needs to be enough room to move people from the south stand for cup games.
https://www.ccfc.co.uk/news/2024/march/news-sky-blues-fans-to-be-in-south-stand-for-all-remaining-home-games/
Good to have an explanation for why the away fans can't be moved