You'll only cause an accident if the faster traffic is driving too fast for the conditions and/or not maintaining sufficient distance from other vehicles, especially your vehicle.

You could ram the other vehicle. In that case no amount of safe/defensive driving would stop that.

But a safe/defensive driver will go as slow as you do if you merge in front of them.

You're saying that you never exceed the speed of traffic in the lane next to you, by even a little bit?

If you exceed the traffic of the lane next to you, you will have low "following distance" to it, and a deceleration disadvantage. Plus, humans have reaction times.

I'm saying that if I exceed the speed of another vehicle and that vehicle merges into my lane or I merge into theirs, and I hit their vehicle from behind, I'm at least partially at fault.

If their vehicle is fully in the lane, I'm almost certainly going to be completely at fault.

I'm saying if you ever exceed the speed of a lane next to you, a vehicle in that lane can force you to crash.

Yup. Relative speed doesn't matter. A vehicle in the lane next to you can force you to crash.