I'm 200lbs ready to ride and I have only noticed stiffness issues with some carbon wheels and some 35mm carbon bars. Both of which can degrade the ride quality by transmitting more vibration than less stiff alternatives. As far as cranks go I have over 5yrs on Next SLs with no issues and just got a set of Next R's at the start of this summer. The cranks and RF's BBs have worked well for me both threaded and PF varieties.
I just got a Boost bike and can't tell any difference from my 100/142 bikes that I can trace back to the wider hubs.
I'm shopping for a hardtail at the moment and I am doing my best to find one with a pleasant amount of flex for my weight/power and avoid an overly stiff frame.
The MTB industries constant marketing spew about more and more and more stiffness is stupid. You don't want the stiffest bike possible. You want the various components of your bike to be appropriately stiff for your needs. That gets too complicated to discuss in an advertisement sound bite so we are left with "MOAR STIFFERER THAN EVER!" ;)