You need far fewer people to maintain an edition than you do to create it in the first place. It's probably as simple as that.
Common reasoning, seriously flawed in context of long term endeavors.
Producing knowledge/information/content results also in certain culture and information barrier one has to scale to join the group of creative people. Once you fire people who made the product in he first place, you will have to deal with severance costs (of those leaving) and then introduction costs while hiring new developers.
Since there is time gap between these two points in time, it is quite often not factored in enterprise cost plan... however, cost is cost, and while clever accounting people can hide it, it is still there. Additionally, replacing creative people produces significant risk of damaging the brand - it is just betting that new folks are not worse that veterans who left.
To put it short: extremely shortsighted policy, results in short time gains at the expense of longterm profitability and quite often quality.
Oh, and it's evil - an employee is a commodity, not a person according to this perspective.
Regards,
Ruemere