Maybe because the Epic thing was nothing to do with Sony - despite the unproven marketing theories. You don't pay somebody to market your upcoming product then ghost the whole event on your social media. The Unreal video was not promoted by
@Playstation, @PlayStationEU or their YouTube channel but the new Studios logo was.
We've heard from reliable insiders, not contradicted by the recent Sony financials and estimates, that Sony are not expecting to sell a lot of PS5s at launch. Despite their verbal commitment to Generations this is not a typical cut-it-lose generation transition. I reckon Sony more than happy with PS4's mad success and are content to let that train run as long as they can. If PS5 is in short supply, relative to demand (which is unknowable) then less disappointed people (not able to get a PS5) is good.