Tiger I think you’re being pedantic, they linked to Whiskers (metallurgy) not Whiskers (electromigration). There is a difference! But it’s not super clear cut, which is why I took the time to write about it.
Electrons do not always move at the same speed in a given metal. A lot of things affects mobility, but the E field is very important too. Both things combine so that electrons do not always move at the same speed in a given metal. But you can simplify in an IC world because there you’re riding the saturation velocity basically always, which is why I assume you keep claiming that.
I want you to know that your experiences from your education and job are valid - you do deal with whiskers in ICs, not denying that; the fact is that whiskers due to stresses and strains aren’t called electromigration which is what the original comment says.
“A similar thing also called whiskers can happen inside ICs and has been a known failure mode for high frequency processors for many years. I work in chip design, and we use software tools to simulate it. It’s due to electromigration and doesn’t rely on stresses but instead high current densities.”