I haven't really worked this out fully yet but I've noticed that whenever a capitalist economy begins to reach the limits of market expansion and employment the whole system tends to go into a decline until new markets are found and new sources of labor can be exploited. What I mean is, to increase profits you must do one of two things: increase production extensively (via increased employment of workers) or increase production intensively (through improved productivity.) Both of these strategies assume that there are untapped markets that will buy the increased production.
The fundamental problem is this: what if existing markets are more-or-less saturated by existing industries? Your only option in this case is to improve productivity by pushing down the value of labor. That's what we're seeing in many industries today. But this is unsustainable long-term, since every worker is also a consumer. The depression of wages is the depression of buying power and markets.
Also, this article might interest you.
https://americanaffairsjournal.org/2017/08/capitalism-without-capitalists/
Aside from economic incentives that encourage an overworked and demoralized employee base, the nature of modern capitalism is becoming more bureaucratic than entrepreneurial. That means the real strategic decisions and policies of a company are increasingly decided by those who primarily see enterprises as an entity from which resources can be extracted and later abandoned.
>The larger and more inefficient a firm grows, is the tendency towards the latter?
Probably. To me it seems like a combination of bureaucratism and conflict of interest. There is no reason for company managers to have any loyalty to their employees nor vice versa. Different levels in a firm have differing incentives that push them in opposite directions.