Linkshells get used primarily for hunting and cross-world linkshells sometimes get used for other activities like maps, statics, extreme and savage content, but discord is where a lot of communication happens. Every free company and static usually has one and finding people for certain content can be done a lot easier through discord because they might not be logged in right now, but you can communicate with anyone from your free company that is logged in.

You can find free companies and linkshells that are recruiting at https://na.finalfantasyxiv.com/lodes...munity_finder/

Party Finder actually is cross-world and is a lot better for social interaction because communication usually happens while the party is filling and sometimes to discuss strategy. Party Finder is one of the most common ways to get people on your friends list and is used to advertise all kinds of content from raids and dungeons to maps and roleplaying.

On Balmung you can find a lot of people in shout at Ul'dah. Fellowships do get used a lot, for example people advertise their statics and roleplaying in them, sometimes people ask for help with their class or look for a few friends, but you have to look through all of the meme ones to see them.

Extremes are part of the mentor roulette although this version of extreme is synced a lot higher than the item level with an Echo buff that can reach a 30% stat boost, which can make it very easy to clear some of them.