Am I underestimating what is possible or are you under estimating what becomes possible when you spend those millions of years developing technology that could

Am I underestimating what is possible or are you under estimating what becomes possible when you spend those millions of years developing technology that could feasibly pull off any of those interstellar extermination methods? The technology necessary to reach out and destroy another civilization light years away cannot be developed in a vacuum. No matter how you accelerate the nuke, navigate it or protect the payload from the harsh realities of relativistic flight, you will develop an entire canon of technologies and an understanding of the universe that before you would ever be capable of identifying, let alone destroying, another intelligent civilization.