I quite clearly remember being impressed by a bard AoE'ing all/most of kerra isle in 1998/early1999. It caused me to travel to blackburrow, die under the waterfall, and just give up on playing that character ever again, I was still bound in toxxila. I gave up on the character, because I needed GM assistance to travel on boats, because my computer was too shitty to zone fast enough to stay on the boat when zoning. I will also say, I believe in my non-evidence based anecdote the bard was debuffing 10+ mobs but may not have been able to effect them with pbaoe damage spells (in the anecdote the particle effect I remember was the shiny clear/silver/blue one of debuffs). As a result I'm sure pbaoe debuff spells were working, for sure. It's possible the bug only effected the damage spells not the debuff spells. There's absolutely no evidence in the quoted post about debuff pbaoe, it only mentions damage songs. In fact my GUESS would be that my memory was specifically of the song
http://wiki.project1999.com/Largo%27s_Melodic_Binding
Even if the bug was fixed in September, it may have been introduced later than launch.
By September 1999 the boats were also fixed, so my non-evidence based anecdote couldn't've happened then.
This said, 'most' of kerra isle is closer to maybe 10-15 mobs than 25 or 50. I'm not sure how the number 4 was reached. It almost can't be 4, since pbaoe spells were specifically the only type of spell that could effect more than 4 targets. I don't see any evidence to set the number to 4, even if it should be less than 25. In 1999 most bards wouldn't've wanted to swarm 25+ anyways because of lag and bad computers making groups that large more dangerous.
Not to mention the "evidence" in question is just blatantly incorrect, the bard who wrote that seemed to think a rain spell could trigger 12 times (4x3), when rain spells can only trigger 4 times (3x1 2x2 or 1x4). If you read the section of his post where he mentions the number 4 he seems to specifically think casters are using rain spells as AoE spells. If the "proof" from 1999 is a quote where a bard confuses the numbers 4 and 12. I'm not sure why the number 4 is the one that's seen as correct. The bard specifically seems to be confusing the situation in which a rain spell is used on a single target and triggers 3 times in 3 "pulses" with a similarity with the fact that bard song pbaoedot also is balanced around 3 "pulses". He's just incorrect though.
His mistake is quoted by me below for reference:
"What DDD has going for it is the speed to cast it, two and a half seconds,
and the fact that it delivers all of it's damage at once, rather than
requiring the target mob stay in the rain area for all three pulses most AOE
requires. It's also point blank, working just like any AoE bard song, the
four closest mobs will be in the effect radius."
I'm also not entirely sure why classic bards need a nerf (although I am a big fan of the nerf on pbaoe from 50-25 because in 1999-2001 on dialup and with single digit megabytes of VRAM no one would've been insane enough to pbaoe 50 enemies). During kunark era I'm 100% sure bards could charm swarm kited. Which is even more effective than pbaoe swarm kiting this tactic already won't be possible at any point in p99's timeline due to social aggro changes that apparently can't be fixed. Or at least I assume that's why social aggro works this way on p99.
I don't play a bard on p99, I don't pbaoe kite, I don't think it's a fun way to play the game, and in 1999-2001 era GM's basically outlawed typical bard swarm kiting if anyone but the bard was in the zone and wanted to play. It was done as part of the play nice policy about zone disruption. I understand p99 doesn't have as large of a gm staff, and a nerf to this type of play totally makes sense. The number 4 though just makes no sense it doesn't seem like it can be classic. If the bard we're quoting from 1999 confused the numbers 4 and 12, I'd say 12 would be a better compromise. In the quoted "evidence" the bard is describing what would be the number 12, despite him actually saying the number 4. Or if you're deadset on making it 4. At least leave pbaoe debuff effects alone in this change and leave them at 25. (Pbaoe effects is a fringe case no one cares about, but IMO it would be a more classic choice of numbers, that is much more well supported by the available evidence). Basically, since this sort of thing was frowned upon by sony staff in 1999-2001 era, I'm totally fine with p99 staff ruining it. It's just that the so called evidence isn't as specific as I'd like for the purposed change.