Whether the reason of strategic (like your example), internal politics, insufficient knowledge.... The point is that there is a local equilibrium, and most mature firms are at this equilibrium.
More resources via Ai, at first order, goes after that diminishing returns part of the curve... which is a cliff especially for highly resourced firms topping the S&P500.
A lot of Ai-optimist:s " mental model" of the economy do not account for this stuff at all.
"Save time/money" outcomes are not similar at all to "make more stuff" outcomes. Firing employees does freeze up labour... but reutilizing this labour is non-trivial... as this article demonstrates quite well.