My experience with normal raiding guilds is that they are friends and family groups who are mostly there for socialization. Bosses will die when they die, they just want to goof around and tell jokes in discord while trying to kill imaginary dragons. Those people probably would indeed run LFR once to see the raid if it was available earlier, but they would still go to their normal raids because for them raiding is far more about being social than gaming.
And yeah would love Open Raid back. There are several discord communities that do the same thing but OpenRaid had better tools. It's really people who would like to schedule a PuG so to speak; they don't mind raiding/doing dungeons with strangers, they just want to be able to plan that ahead at their leisure. That said, Gen Z prefers apps to in-browser utilities which complicates things.
However the reputation part of Open Raid could never be done if this was made available by Blizzard imo. They would only allow perfomance-based and entirely data driven ratings.
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Not recruiting or anything but have you tried a discord community?