That short list of poskim at the end were citations of shitos that say more or less that “ervah” described in that Gemara in Berachos is subject to societal norms.
One more thing. Sa’ar b’isha ervah is not some obscure Tosefta somewhere. Therefore if it were true that the halacha we are discussing is an outgrowth of that, I would expect it to be noted in the rishonim. Can you show me even one rishon who says so?