Chumrot??

Question

"...Whoever looks into the Shulchan Aruch will find that a majority of the laws are Chumrot (extra restrictions) of the acharonim (later Rabbis) without any basis in Sha"s (the Talmud)..." Pardon my lack of understanding. What Acharonim is he referring to? Can't be the Mechaber and Rama. The Nosei Kelim? Speaking of chumrot, the author of the above wrote a kuntres banning Indian hair wigs about 30 years ago. Didn't work then, I wonder why now?