It's all about getting visitors to come back to a website. People consume so much content every single day, so it's extremely easy for your website to be forgotten in all of the madness.
By having a newsletter you get recurring visitors, not just fly by clicks.
I always found setting up a git server from scratch to be quite confusing and I also like the webui that gitea offers.
But recently I have also started moving some of my github projects there so having a link (with a readme and everything) that I can share with others is important.
Yup rss is very scary