The AoE aspect wasn't the draw of Harmony. What mattered is Harmony actually worked. It COULD get resisted though (this is another thing that needs to be changed on p99). Not exactly sure on the level limit, but a Level 5 Druid couldn't just go Harmony a Level 50 target. At least not after very early classic, when they changed a few previously unresistible spell lines to be resistible by deep red cons.
All other lull spells in classic were quite weak. Very high resist rate, which lead to a critical fail frequently. Unless you were near a zone line or had a Cleric to rez (or were a Necro with FD lulling undead), it was generally not worth risking lull if you weren't able to break a camp with root/mez to begin with. Lull was mostly just something you would hope to high roll with to save a bit of time/mana, since if it worked a lull meant casting less root/mez. If it didn't work after the first couple casts, which was common, then you'd usually just stop.
ALSO, regarding this theoretical "7 minute Pacify duration", the Lull line is supposed to have a chance of ending early, every tick.
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