There is an esoteric concept that has some dynamics that explain this phenomenon somewhat. Not to get to into the weeds (the origins of this concept are esoteric religious ideas - I mean this secularly, as it relates to business entities) but the concept is an 'egregore'

https://en.wikipedia.org/wiki/Egregore#:~:text=An%20egregore....

I don't see it on the Wikipedia page, but the theory that explains the degradation of a companies original mission statement can be summarized as this: "Within an organization(egregore) there exists three classes of individuals... the primary two of which are those that serve in the name of the egregore, and those that serve the egregore directly, the third (a smaller %) being those un-loyal to the current structure and would change the egregore to suit their needs. Of the main two: The dichotomy can be spilt along lines like developers/founders vs marketers/sales, where developers are interested in serving the mission statement and developing a good product, and marketers are interested in growth and survival, at the expense of everything else. So when the developers/founders leave, the vacuum that is created is filled either by those that would change the egregore, or corrupt the mission statement in the name of growth and profit."

This is a simplistic model - with a fair bit of predictive and explanatory power. I have found it useful to describe that shift inside a corporation.