I worked on Capitol Hill for (too many) years. Every office had some constituents who sent letters every day or so and, yes, they were considered to be annoying crackpots. There really is such a thing as the “little boy who cried wolf.” When someone spews outrage on a daily basis, and apparently has nothing better to do than write to a legislator, it’s difficult to take that person seriously. The individual would always get a response and be treated with respect, but the entire office did a collective eye-roll.
My congressional years pre-date email, so I don’t know how e-communications have affected constituent communications. Way back then, the order was:
1. (Highest) Visit to the D.C. or home district office, or appearance at some public event to meet the legislator
2. Personally-written letter
3. Phone call
4. Pre-printed postcard or form letter, from some organization, that required just a signature and stamp
5. (Lowest) Signing a petition.