i dont think they are trying to do that dont be so snappy there just giving input
I don't think so. I don't think they are so unaware of relative skill levels, capabilities and such to actually think the Spitfire Mk I and P-40C are good perk farming aircraft. Those posts were classic "look at me" posts disguised as advice and they were bad advice. If a new player, looking to earn perks were to follow them and grab that P-40C he'd hardly earn any perks because it is so hard to be successful in those aircraft.
The very notion of a perk farmer is a unit that has effective high perk point per time unit generation, something the Bf109s generally excel at. Slow fighters that yield mostly assists and that require skill to survive in do not make good perk farmers. Years ago, before the Spitfire Mk I or P-40B was added, Citabria (as I recall) set out to hit a 5/1 or 10/1 (don't recall which) K/D ratio in each fighter and the only one in which he could not do so was the C.202. Too many of the things that ought to have been kills were turned into assists by other players using large banks of heavy machine guns or cannons and his final K/D ratio was less than 3/1 in the C.202.
The C.202 out performs the Spitfire Mk I and P-40C by a noticeable margin and if Citabria, one of the better players, had his success level heavily curtailed by the C.202, what is Joe Average going to do with those fighters?
The P-40C and Spitfire Mk I, and all other fighters in that category, are not perk farmers. They are challenge aircraft that one uses because one either really likes the aircraft's history (Flying Tigers, Battle of Britain, ect) or because they want the challenge. Recommending them as perk farmers does a disservice to anybody who might be using the discussion to learn and be more effective at their chosen task, in this case earning perk points.