After going through the code, it appears to be unused. this pref does nothing.
There are many dead prefs in the internal list - one more reason not to go looking for "Secret features" in the internal section. Trust me, if there was a feature lurking in there that was really valuable, we would expose it in the "public" app settings. Most are there for testing and diagnosis not as features.
I like leaving the tracks empty of FX by default and adding what I want (usually NOT the Sonic Foundry plugs). Also nice to have control over the splash screen... ; ))