77,000 + spams might not do much in the short game, but it might lead to a larger percentage that ordinarily would not write at all to take the next step and get more involved at a deeper level.
Sometimes all it takes is a small, seemingly inconsequential, first step to motivate folks into doing more.
The first time I ever wrote a legislator was through a similar standard form letter like this years ago. After that, the gate opened and I have maintained a continuous flow of both emails and mailed letters over a period of years.