Partly true. cow is beef, pig is pork, sheep is mutton (but rarely if ever eaten), but lamb is always lamb, never mutton, otherwise "mutton dressed as lamb" would make no sense.
Venison is still venison, (who's ever heard of buying "dear meat"?) Chicken was always chicken as a meat, "poultry" refers to the livestock as a collective noun.
I beg you to go to your local butcher (or butcher's counter in your supermarket if you don't have a butcher) and order a kilo of "swine flesh" and see how widespread that usage is!
Whoever wrote the section of the wikipedia article you quoted clearly doesn't speak English as a native language, or was having a joke at your expense.
Venison is still venison, (who's ever heard of buying "dear meat"?) Chicken was always chicken as a meat, "poultry" refers to the livestock as a collective noun.
I beg you to go to your local butcher (or butcher's counter in your supermarket if you don't have a butcher) and order a kilo of "swine flesh" and see how widespread that usage is!
Whoever wrote the section of the wikipedia article you quoted clearly doesn't speak English as a native language, or was having a joke at your expense.