Kinda strange. But understandable. It looks like PS4 already peaked so no need to waste resources on its promotion anymore. Focusing on PS5 instead is a way better strategy at this point. I expect that they will have PSX next year though.
P.S. I disagree with the claims that E3 is irrelevant. I think they had their best year ever and the attendance grows every year, so E3 will only get bigger.