I agree broadly with this, but was surprised to see the staff software engineer callout. Then OP linked to some other docs about how to avoid being stuck in rut

I agree broadly with this, but was surprised to see the staff software engineer callout. Then OP linked to some other docs about how to avoid being stuck in rut at "merely" useful. At my job we call that "You can't get promoted to next level by doing the job of someone 2 levels above you."