Double dipping is usually a term coming from MMOs or ARPGs. Most of the time it refers to buffing you in 2 ways at the same time while actually only increasing 1 stat.
With the terrible upcoming patch and the crew skill rework, the major qualification of your crew affects the effectiveness of perks as well. That means food not only buffs your crew by the usual bonuses for having 10% more major qualification, but it also affects the effectiveness of individual perks like Recon, Camo, the new perk buffing your reload in close quarters combat, the new perk lowering cooldown times for consumable, the new perk increasing engine power and top speed, the new perk increasing criticals and crew injuries of enemies, ……
Vents are one of the most popular equipment pieces. In higher tiers where you dont need optics to reach 445m view range, it absolutely dominates. Crew perk double dipping decreases equipment build variety. Vents will be a must have.
Food is already absolute broken. Food gives you 10% on the major qualification, which equals 2 vents. So you and your buddy can drive the same tank, with the same crew and equipment pieces, but he actually has 2 additional Vents compared to you. Food users drive with 5 equipment slots for the price of 20k credits every game.
Shooting gold rounds is something F2P players can afford to do from time to time when it is necessary. But you absolutely cant afford to play high tiers regularly while running food without Premium. I speak from personal experience, I am pure F2P player. According tomato.gg with 2484 WN8, being better than 95.9% of players, I ABSOLUTELY CAN NOT afford to play with food.
Now everyone running with food spot even further, because he buffs Recon and Situational Awareness a second time. With the bonus of 2 additional Vents. Everyone with food will reload faster in brawls, because he buffs the new perks that lets you reload faster with an enemy withing 50m. Everyone with food will have an even faster cooldown on their consumable, because food buffs the new perk Practicality a second time.
I vividly remember Iyouxin on one of this streams, talking with his chat about a no gold shooting challenge, but begging chat to let him have food, because food is the majority of times a far bigger buff than shooting gold.
TLDR: Double dipping of crew perks is absolutely stupid. It makes vents mandatory, pushes players very hard to use the already incredibly powerful food consumable and by that increases the gap between newcomers/casuals and the paying whales.
It is just a cheap way to press more money out of whales, while shitting on the gameplay/fun.
Edit: I really think this needs to be called out specifically as well, because the new crew perks system is not only terrible for all the new skills, but also because of this double dipping.