S/C takes power to make power. Couple that with belt issues, after cooling issues, space issues. It's much easier and cheaper to make a well designed turbo system then a custom S/C kit.
And I don't know what you're talking about 'random power' of turbos.. if you have someone properly match all the parts of a turbo kit up to your power goal you'll have almost an equal power band as a S/C setup.
New turbo technology has simply come a long way to think that turbo system have to be peaky in nature. That and there are too many people that just throw on GT40's.
Modern ball bearing turbo + electronic PWM boost controller + very linear boost and power levels.
Just something to think about.