This is the best thing to do. Let them waste their money on printed, mailed ads, and use it to taunt them on the internet and expose how they badger and milk their cattle customers.
I feel this is the most environmentally friendly thing to do in my experience because it was the only thing that stopped me from being spammed by Comcast, former house owners, etc. it's amazing how quick businesses will stop sending you junk mail when you start sending it back.
Which only works if you have a product that doesn't suck. They should spend more money building their network out so it isn't 2002-era DSL oversubscribed 😂