They mostly try to protect hardware implementation details. Another example was how hard it is to get data needed for writing good drivers, another firmware. Ev

They mostly try to protect hardware implementation details. Another example was how hard it is to get data needed for writing good drivers, another firmware. Even that most companies don't want to share for fear it leaks some aspect of the design. Finally, for Intel ME backdooring all CPU's, there's a decent chance they're paid a fortune by one partner in particular to keep it there with buggy, obfuscated code. That's on top of ordinary reasons.