Squeezing grapes for grape juice is prohibited on Shabbat because it was done in the Temple. You might think that squeezing grapes, honeycomb, and cooked vegetables follow the same law, but they do not. For example, squeezing cooked vegetables to make them taste better is completely permitted, but getting their juice might be prohibited by the Sages.
Rabbi Yochanan was drifting while his two students discussed natural explanations to some questions they had. For example, they asked, why are Holidays in Babylon more joyous than in Israel? Because they are poor and reserve celebrations for the Holidays, and so on.
At that, Rabbi Yochanan awoke and said, "Children! If something is clear, certain, and wise, say it. If not - do not say." Then he gave the Torah explanations. For example, the Holidays in Babylon are joyous because they were not included in the curse of "Your new moons and Holidays My soul hates - says the Holy One." That applied only to Israel but not to Babylon.






