Be careful about "unsubscribing" to various services.
They will unsubscribe you, but then they also have all of your information (name, address, anything else) on record and confirmed. They can profit when the sell that data to another mailer "service". It's like a Hydra.
Key difference is that Bitcoin people want/need their numbers to go up,up,up as a measure of success.
Here, we are hoping to cultivate a healthy community (at either/both the instance and fediverse level). From my experience on various subreddits, focusing on growth is not a good way to do this.
Communities are defined more by who is not allowed in than by who is in the community. Lemmy phase 2 kicked off back in June, and it still needs some time to find its footing at a sustainable rate of growth.