Is it hard to believe that the new team's salary fluctuates by as much as $50k solely due to negotiation?
If a company wants someone, and that someone doesn't want to go, negotiation and salary fluctuation is what happens. I think $50k is on the low side of what the disparities could end up being. (See the recent craze of poaching AI talent.)
I'm being hired for my software skills, not my negotiation skills. The fact that negotiation is so important is cargo culting from business-types who benefit from it.
(I happen to be quite savvy at negotiation, but I've seen many shy people exploited because they're not as cocky as me).
More to the point,
1) If my team was hiring a new guy with skills indistinct from mine for 50k extra, and I found out about it, I'd ask for a raise. If they refused, I'd quit on the spot.
2) If the skills are indeed a whole class above mine, they'll probably have a different title, and it's much less of my concern (I wouldn't call it "a fluctuation among members in my team").
Information may not always make things better, but it always -- no exceptions -- makes a market more efficient.
Moreover, stop focusing on two team members fighting against each other. The big prize here is employees finding out how much their bosses make, especially when it comes to "tightening belt" periods. I don't honestly care if Jeff-next-door is getting 20k extra because he plead for his newborn, but I absolutely care if my salary gets frozen and my boss gets a bonus.
Opponents to salary transparency are basically arguing for an inefficiency that favors higher-ups, preying on the ignorance of less resourceful subordinates.
I'm questioning whether this raise will usually immediately make you the best paid person on your new team.