Hi theATL.social (Mastodon) and yall.theATL.social (Lemmy) friends. Your friendly admin, @michael, here.
Currently, theATL.social blocks two domains from federation but does not utilize any block lists. the Lemmy yall.theATL.social does not block any domains.
My general admin philosophy is to let users decide what content they want to see, or not see. However, the Mastodon UI can make the adding/removing of domain block lists a bit tedious. (There are some tech/UI-related options to make this easier.)
On the other hand, I am personally not a free speech absolutist, and there are limits to what content could/should be relayed through theATL.social's servers.
For example, illegal content, instances dedicated solely to hate speech/harassment, etc. To that end, the Oliphant Tier 0 block list offers a "floor" to remove literally the worst instances operating on the Fediverse: https://codeberg.org/oliphant/blocklists/src/branch/main/blocklists
As your admin, I don't want to make any unilateral decisions - rather, I'd prefer a user/stakeholder conversation, with as many Q&As as helpful.
Likewise, I am not a free speech absolutist- limits should be in place to censor the most repugnant content. Using the Tier-0 list for instance-level blocking is a good approach: light touch, using globally accepted standards.
For the rest, if a user doesn't want to see content from a user or domain, they can block either/both at their level. As a user, I should be permitted to follow who I choose, consume text/media I wish to see, and block content that which offends me. I don't need an admin making those decisions for me. An overzealous admin (or instance leadership) blocking domains at the instance level that /they/ find distasteful is far too arbitrary.
However, the admin must balance risk- they own the underlying infrastructure and could be accountable for the content transacted and stored- from both a legal standpoint and with respect to the broader community. Consider a situation where a user is acting against de facto global content standards and the admin does nothing- all users of the instance are at risk of global defederation.
I feel the guidelines established to moderate theatl.social are broad enough to foster open dialog, but also protect the instance from broad defederation. Adding a Tier-0 block is a sensible addition.