I don't remember it being more polite in the past. Both sides were yelling past one another, calling the opposition insane or evil, and not winning any converts over to the truth. The difference was in the past you didn't have so many ignorant NPCs with no stake in the matter taking a side (most people didn't care about politics or "social justice") and institutions like academia and media may have been biased but weren't so transparently on one side. Unless you were talking to a known lefty like Donahue, it was correctly framed as a political debate with opposing viewpoints. Now it's "far-right White Christian misogynists vs. human rights". The extremists were always like that but the extremes have expanded. Even back then liberals were probably taking the typical "you must tolerate me until I'm in power, then I won't tolerate you" approach.