Having been here since 2016, I can tell you there is definitely no such thing as a consensus on usage of content warnings on the fediverse. It's a decentralized network that doesn't belong to any one party, so by definition there is no single culture on it. Different corners have different expectations and customs.
@Gargron I think it's a great discussion (though I seem to get blocked by someone every time I wade into it). I'm still very interested to see a section on that in an open source "constitution" of sorts for the fediverse. Servers could adopt the constitution in whole or in part.
@Gargron Then when people enter a dispute about content warning or no content warning, they can check their respective server rules and use that to settle it. E.g. if the rule were "content warnings are encouraged but not required. It is not recommended to chastise someone for their choice of content warning or not. It is encouraged to inform your followers about content warnings and when to use them..." Not necessarily suggesting that rule, just a rule in that vein.
@escarpment @Gargron
What if they're on different servers?
@BenAveling @Gargron This is a similar question to the one facing the framers of the US constitution. Article IV has a bit of their answer (the full faith and credit clause). The federal govt of the US often has jurisdiction when disputes cross state lines- should there be a "federal govt" for the fediverse? Or is the answer "be careful out beyond the safety of your server: other servers have slightly different rules that we can't protect you from."
@escarpment
And then there can be other countries, even if there was a "federal government" for the Fediverse, other servers could not abide to it, so it doesn't really solve the question. No need to add back centralization, having tools to work with is more important.
@BenAveling @Gargron

@Varpie @BenAveling @Gargron Perhaps. I agree- there would be servers that do not accept the constitution. There could be servers that accept a different set of rules that is unpalatable to the majority of instances which adopt the constitution and therefore they defederate from those instances.

I guess the question is: could some centralization actually be good? (A conference; a virtual conference; a meet up for admins; a global support team that helps admins fight fires).

@escarpment
For issues about "how should content warnings be used"? No, I don't think so. If a specific server admin decides that it is an important rule and does not federate with instances that don't agree, then so be it, but it shouldn't be a global issue.
@BenAveling @Gargron
@Varpie @BenAveling @Gargron I guess what I'm envisioning is that there exist many flavors of the "Mastodon Constitution", similar to software licenses like MIT or GPL. And each server chooses a well known one, or rolls their own. But potentially they all share certain things in common.