The information that I have submitted to the OP is quite pertinent. Any extra weight added to the aluminum frame, whether the cyclist tends to be overweight himself, or not, is going to add additional stress to the aluminum frame. Aluminum bicycle frames can be designed to endure many cycles of stress. Aluminum has both a smaller fatigue strength and yield capacity, than steel. The number of stress cycles for aluminum is indeed a finite number. This is NOT the case with steel.

For example:

Imagine drinking from a pristine pool of water that's pressure sensitive and in balance with the atmospheric pressure of the cold reservoir supplying it. Everytime you scoop a cup of water from the pristine pool, the reservoir replenishes the pool, restoring the pool to its original volume. That's steel.

Now imagine a pool which is only supplied with an air filter and a cooler. When you scoop up a cup of water, you've just depleted your water supply with no promise of restoring your water to its original volume. The only question here is the following:

What was my original volume of potable water?....That's aluminum!

-And that's the question with which all aluminum framed bicycle owners need to concern themselves...

The longer you use your aluminum framed bicycle and the more force(s) that you subject it to, the faster it reaches its fail date. If you cycle frequently upon an aluminum framed bicycle, then you're drinking larger volumes of water and thus, depleting your pool more rapidly. If you use your aluminum framed bicycle in DH MTB races, then you're depleting your pool much more rapidly.

So there's no wrong information here. A 200 lb. rider will indeed subject his aluminum framed bicycle to more stress cycles than a 175 lb. rider. However, the question remains, how many stress cycles will the modern-day highly technologically designed aluminum framed bicycle endure?...Will it be thousands or millions? ...Just how deep is that aluminum pool?

No matter how deep it is, the steel pool remains much deeper!