When a company seeks to acquire another company, the executives of the target company are sometimes promised and given a disproportionate share of management roles in the reorganized entity as enticement to grease the acquisition. The alternative is more expensive payouts. And of course, no matter which approach is taken, cash will be tight post merger so there'll naturally be an emphasis on cost cutting and "synergizing", which McDonnell Douglas executives were well practiced in, likely drawing favor from the board, despite that it was still 2/3rds Boeing post merger.
Also, despite the narrative, it may very well have already been the case that Boeing's culture was going down the gutter, its acquisition of McDonnell Douglas a reflection of that rather than the root cause.
EDIT: Here's a 2002 article that suggests it was all of these phenomena--disproportionate leadership roles, a claim to cost control expertise, a skittish board, and evolving business strategies. https://www.seattlepi.com/business/article/Hard-nosed-Stonec... Some former McDonnell Douglas executives, like Boeing President and COO Harry Stonecipher, were well placed to take control when the inevitable cash crunch happened. Stonecipher replaced the Boeing CFO with a GM executive. See also this contemporaneous 1998 article describing the same event: https://archive.seattletimes.com/archive/?date=19980715&slug... That article says it was Stonecipher and the board chairman, Phil Condit, who forced the CFO out for his overly conservative accounting. Condit, AFAIU, was also CEO at the time and had been CEO of Boeing prior to the McDonnell Douglas merger. In fact, Condit led multiple acquisitions before MD, which suggests to me he and Boeing were already following the "acquire rather than innovate" playbook.
Also, despite the narrative, it may very well have already been the case that Boeing's culture was going down the gutter, its acquisition of McDonnell Douglas a reflection of that rather than the root cause.
EDIT: Here's a 2002 article that suggests it was all of these phenomena--disproportionate leadership roles, a claim to cost control expertise, a skittish board, and evolving business strategies. https://www.seattlepi.com/business/article/Hard-nosed-Stonec... Some former McDonnell Douglas executives, like Boeing President and COO Harry Stonecipher, were well placed to take control when the inevitable cash crunch happened. Stonecipher replaced the Boeing CFO with a GM executive. See also this contemporaneous 1998 article describing the same event: https://archive.seattletimes.com/archive/?date=19980715&slug... That article says it was Stonecipher and the board chairman, Phil Condit, who forced the CFO out for his overly conservative accounting. Condit, AFAIU, was also CEO at the time and had been CEO of Boeing prior to the McDonnell Douglas merger. In fact, Condit led multiple acquisitions before MD, which suggests to me he and Boeing were already following the "acquire rather than innovate" playbook.