Its not wrong to say its advantageous to the R-27 though xD
Certain missiles are inherently having their maneuverability limited while others are not for no actual reason from the sounds of it. The R-27 is a missile that gains from this modelling decision as are some other missiles.
By definition, this modelling decision to only go to single plane limits of missiles is inherently advantageous to single plane only missiles by way of being disadvantageous to dual plane missiles. Theres no actual valid gameplay reason why dual plane missiles cant have their dual plane maneuvrability modelled in-game, it is SOLELY a design decision, just like the design decision of missile diamonds existing when missile motor burns, even on smokeless motors, is advantageous to low burn time motors despite things like massive base drag increases experienced by missiles when their motor burns out irl NOT being modelled in-game.
Regardless of how you choose to cut it, if a gameplay decision has inequitable results on missile/vehicle performance, there will inherently be certain weapons/vehicles ingame that win, and other that lose from that.
Pretending its not advantageous to the R-27ER (which has massive single plane maneuverability but doesn’t use dual plane) or other single plane only missiles, for things like AIM-54 to be modelled single plane only, with a MASSIVE 8G cut to its maneuverability (32% lower than it should be) is disingenuous.
There’s tons of these examples in WT, both throughout its history and even now. Things like late WW2 German tanks which had negative modifiers on their steel to “imitate poor steel quality”, Russian tank shells having higher chance to set things on fire/detonate fuel/ammo long ago, current spalling mechanics favoring Russian tanks, garbage NATO composite modelling, spotting mechanics, 2 seater jet mechanics, exhaust heat modelling, etc… All are inequitable modelling decisions which disproportionately favor one nation above the rest and are really becoming a sore point for players who play other nations in-game.
Its irrelevant how many vehicles/weapons are DIRECTLY affected by these modelling decisions negatively impacting them, as all adversary vehicles/weapons are POSITIVELY impacted by said decisions, and pretending that isn’t so is just outright lying.
These modelling decisions are also why I am EXTREMELY worried about the implementation of the R-77 in WT, as it is likely a rather poor missile in the specific circumstances of WT air combat (low altitude transonic or even subsonic launches, and only holds advantages at high supersonic launches over contemporary missiles, but with the current simplistic drag model being used, and more specifically gaijins track record, there is no reason for anyone to believe they would actually model this disadvantge.