With near perfect backwards compatibility, the amount of software that society can consume is in effect unlimited. The number of software developers is finite, but the amount of software they can create isn't: only the growth rate is finite. Thus society can benefit from an ever-expanding library of programs which increases overall wealth. Indeed, tool creation is the only way to increase wealth in countries with a flat or falling population (productivity * population = gdp, more or less). In this mode, software is like knowledge. It accumulates and compounds.
With imperfect backwards compatibility you are forced to engage in continuous maintenance of all existing software. Suddenly there is now a fixed limit on how much software society can have, it's a function of how many maintenance developers there are. You can literally reach a limit where things can slide backwards. Problems can become un-automated. In this mode, software is more like oil. It can run out.
Google want to force continuous maintenance because the Android team justify their existence with constant change, and if a platform is full of unmaintained apps then it will feel old and tired compared to a platform full of apps that have the freshest new looks and features. But that often doesn't matter, especially for non-consumer or specialized software used only by a small number of people (but for high leverage impact). Because Google and Apple are unapologetically consumer focused cultures, they care far more about things like how apps look and stuff that's irrelevant in business contexts (consumer privacy).