2) For a multitude of reasons, usually related to biz dev and budgeting, release windows are set way ahead of time. Then a marketing campaign starts months in advance to build up to release. A marketing campaign is extremely costly, and loses much of its effectiveness if it’s interrupted. it might be impossible to build up the same level of attention a second time, and most companies aren’t willing or can’t afford to take that chance.
3) The work remaining that does require creativity, responding to QA demands, porting, redesigns, bug fixing, etc ends up in a crunch by necessity due to 2).