Why did they give wine to Nezirim to drink?
Rashi: This is so they will not instruct you. One who is drunk may not give Hora'ah.
Rashi citing Targum Yonasan: You made your teachers err with wine.
Radak: Not only were you not careful about what I warned you, and you did not open your eyes to what I did with you. Rather, the Nevi'im and Nezirim that were among you for a sign of your Kedushah, you nullified them and withheld from them the Kedushah that you should have learned from them. You verbally enticed Nezirim until they heeded you to drink wine and nullify their Kedushah.
Malbim: This was so there will be no one to teach separation.
Why does it say that they told Nevi'im not to prophesize?
Rashi: Amatzyah Kohen Beis Kel told Amos "Chozeh Lech Brach Lecha El Eretz Yehudah; [? v'Lo Sosif Od Lehinavei]" (7:12-13).
Radak: It says "Tzivisem", for they forcibly stopped them from prophesizing for you and warning you in My name.
Malbim: This was so My Ru'ach ha'Kodesh will not be within Yisrael, and they will not seek the true Emunah and warn against idolatry.
