Without too much detail due to contracts/NDA/etc, slipping a release date is even worse of a bother for others down-chain also. There are planned times for manufacturing, warehousing, distribution, all that fun stuff for the physical versions of titles. All that would basically need to be re-dated from scratch. You can't slip one week, you have to slip at least a month. More for platforms that don't use standard disc formats which are not made locally. (Which hilariously, CP2077 already did slip a month before release.)

Even for digital games, there's still approval processes where the first parties would have to test the game out. This process involves scheduling people for it; you can't just go to the front of the line as there are other games that have been scheduled for certain slots. (Which hilariously, it was rumored that CP2077 was given the 'don't test, push live ASAP' treatment.)

At lastly, all payments from the platforms and retailers are based on the actual release date. Unless there's a specific contract, games are not paid until months after release. Physical preorders don't pay the developers, they just help with preventing over/under stocking. (And digital preorders are... functionally worthless beyond the psychological value.) The release date starts the payment timer. When hurting for cash, releasing can start that timer.

The processes above can really benefit abusers who decide that "making street-date" is the most important thing above all other concerns.