Again, it's not 3 GCDs.
It's 'every Enchanted GCD in the 30s duration of Manafication'. Up to 3 'Melee' combos, if you pooled resources. Unless, by '3 GCDs' you mean 'these 3 buttons on the hotbar, which happen to be GCD actions'
If the request is 'what older fights had space designed in, such that a RDM and 2 Melees AND both Tanks can all be in melee range of the Boss during the burst window', A: A lot of older fights did not rely so much on 'the party has 4 in and 4 out' so much as things like Protean positions where everybody is equidistant from the boss, or the angle of each player around the boss is more important than the distance from the boss, etc. and B: The timing of players' bursts were staggered in older days, so not everybody was bursting at the same time.
I guess this slide needs to be updated to say 'Ranged attacks with magic (and sometimes Rapier)', and 'Melee attacks with Rapier (but can sometimes strike with Rapier from 25y away)'. 'A Hybrid Ranged/Melee style, achieved using high-speed positioning' only holds true if you actually need to Melee, and with this change, you Melee less. It is, objectively, less 'hybrid' than it was before. I fully expect that there will be calls to make the remaining 'actually Melee' Melee combo also be executable from range come 8.0