Most people don’t care about what’s true, something that took me forever to realize. Encountering humanity under the assumption that everyone cares about the truth (or any aspect of empirical and normative reality) is bound to be suuuper confusing until you figure things out. People are literally animals (we forget that), and animals are just trying to survive. Some of them are cute or loving. Not all of them are particularly “good,” and even fewer are willing to sacrifice creature comforts in pursuit of some abstract virtues. That’s why Trump gets any votes.

Hmmm, while I see your point on the phrase, my friend group and I only ever use it on subjective things. Like orange juice or chocolate milk being better, for example. If we're both arguing (in a fun way) and have no good points to change the other's mind, then we agree to disagree. Haha

but there is just no right or wrong answer to every question... sometimes it's just about opinion.

sometimes these questions are trivial (which color of tie should I wear with this shirt) and sometimes they are literally life and death questions (should death penalty be legal)... and there will always be people with opposing opinions on them. "agreeing to disagree" is literally the best possible thing they can do to live in the same society.

I find it really useful to shut down discussions where no one is budging and are just overall a big waste of time. As an example, if I've been trying to convince someone that the earth is round for 10 minutes and they clearly don't have any interest in changing their view, I'll just spare me the trouble and say it. If they still refuse to let it go, I start blindly agreeing with them, that usually does the trick.