That's a fine argument, and I'm sure that if management knew they could get a 70% decrease in load times in exchange for focusing on this one area, they would have done so. But nobody knew. And discovering that would have been expensive.

I'll meet you halfway though: they should have had profiling sessions that pointed to the JSON parsing code as the issue. I imagine that all of their profiling efforts were focused on the runtime performance, not the load time. Simply put, no one did that profiling, and I don't fault them for focusing on runtime performance (which is where the real money is, as Cyberpunk 2077 demonstrated by not having it, and subsequently having their PS4 orders yanked and refunded).