They might have been yelling “BRUUUUUUCE”. It confused me when I watched one of Springsteen’s old concerts and thought the crowd was booing him.

The current three blade design of utility-scale turbines achieves about 80% of the Betz limit, are relatively efficient in materials for their output, and the blades’ pitch can be adjusted to control their speed in varying conditions (eg. during storms). I wouldn’t call their design “incredibly stupid”.