JayMatt wrote: “Even after shecting Rav Zeira, Raba was still going to drink.”
That is actually the svara given for why the Rif, the Rosh, and the Tur paskened according to “ad d’lo yada.” (How they interpreted “ad d’lo yada is less clear.” Perhaps they held like Tosfos, based on the Yerushalmi, that ad d’lo yada is actually a pretty minimal level of drunkenness).
Of course, it is worthwhile to mention the Maharsha, who writes that Rav Zeira didn’t actually die. He says that Rabba pressured Rav Zeira to drink so much alcohol that Rav Zeira became dangerously ill. This is a good Maharsha to remember for Purim.
Mayan_Dvash wrote: “Why, bederech klal, more people tend to go toward the maikal sheetah but here more people gravitate to the machmir sheetah?”
I’m not sure what you mean. In this case, being machmir in either direction means being maikel in the other. If your machmir on getting super drunk, your are being maikel according to the shitos that assur getting drunk. If you are machmir on staying sober, you are being maikel on the shitos that say to get drunk. It is impossible to be yotzei kol hashittos in this case.