What's untrue about it? If you agree to a declaration of Friendship and they ask for a free resource (and they will) and you refuse, they will hold it against you for the rest of the game.
There's a sweet spot where you are large and dominant enough that the AI will look over past transgressions and or fake friendly because they decided it is not helpful for them to openly oppose you.
That however won't save people who declare too many wars or are applying Civ3/4 strategies like oscillating wars where you declare war on everyone at some point and take chunks of everyone and expect to patch things up. That strategy is diplomatic suicide in Civ5. Generally when you reach a tipping point, the AI will hate you, regardless of how powerful you are.
So in reality, there's a sweet spot, which is a moving target depending on your size, your proximity to possible rivals and just how avidly you applied old strategies to Civ5, and a bunch of random factors like Civ mix, and your clique in the game.
A helpful remark would be to point out that
1) declaring war on city states is usually not helpful
2) Check pledge to protect warnings when dealing with city states
3) try not to break promises not to expand in a specific direction after the warning from a leader, break co-op war promises or just any promises in general - like withdrawing from a city state
4) The lay of the land - like civs who are rolled in the game. Some games will just be filled with jerks.
5) You may be trying to win in the same way as too many civs
6) Civs do bribe each other to go to war with another civ. Being absent diplomatically can open the door for an AI to step in and instigate wars against the human player and other AI civs
7) A good early step in the first 50 turns is to try to get an early war going to set alliances. If a warmonger is in the mix, try to get them to DoW on another Civ so they leave you alone. In turns up to 150, keep an eye out on who is dow on who and establish those hatreds by bribing the same parties to go to war again
8) Accept Declarations of Friendships from trustworthy Civs, Ghandi, Sukhotai are generally reliable, Genghis is often not. Try not to DoF with the enmies of your friends.
9) Insert reference to
Bibor's Diplomacy by the Numbers. As a guide on who the warmongers are (generally) who the loyal friends are (generally)
10) Note that Diplomacy variables are subject to RNG rolls but most of the time, the AI will play each leader within a range that makes them quite familiar over many playthoughs.
That would have been a good start