The problem with relic being an incentive to add high level players back into low level content is that it was only really effective during peak log-in periods (basically the rushers after each relic step upgrade).
Going forward I guess they mentioned letting people go into low dungeons with an incomplete party which will help, but there is always a tank and healer shortage even with the high levels thrown in. That's the real low level bottleneck and it's not something high levels help that much with imo.
FATEs do scale to participants the last time it was up; it's much easier to solo most FATEs up to mid 30s when it's only like 1-3 people in the zone and 1-3 people actively doing FATEs. The relic horde doing 200-man FATEs made it much harder for people to clear it after they left, lol.
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