Majority of installs or majority of transactions across all installs? I suspect that the majority of installs are indeed running default configuration, or at least close enough to default that the user wouldn't have looked closely enough to spot the kind of configuration issue being discussed.
Larger installs, which probably do account for the bulk of transactions, are more likely to have been tuned for speed, although probably keeping all of the safety settings at (or above) their defaults. But part of the point here is that in a safe configuration Mongo makes things slower than default.
Larger installs, which probably do account for the bulk of transactions, are more likely to have been tuned for speed, although probably keeping all of the safety settings at (or above) their defaults. But part of the point here is that in a safe configuration Mongo makes things slower than default.