Sony will have released 12 games -including new IPs- during 2024 (counting there Destiny TFS, TLOU2R and Until Dawn thre, which may not count for some people) plus 3 late PC ports. Add there the 3rd party exclusives like Granblue, FFVIIR, ZZZ, Wukong, Silent Hill 2, several indies etc. Plus some top tier 3rd party multiplatforms which are going to be the best sellers of the year, and some random 3rd party games more that may have had marketing deals with them. If all this wasn't enough, there's the PS5 Pro too.
This already is a giant marketing effort, they have been marketing a lot of stuff. They can add a few 2025 games too on top (specially at the end of the year, at TGS and the Doritos Awards), but before that they had to market the 2024 games.
They have a shit ton of releases every year that they have to market. To wait until a year or even less before release to show games help devs because gives them more time to use making the game and not demos for trailers or events, and also saves them from players -who don't have a fucking idea they are talking about- complaining about downgrades if they start to show the game when it's almost complete and being tested, bugfixed and polished.