It works fine.

Game basically works on RNG, with every faction having % chance to declare war on your every turn, even allies.

Now when it comes to AI viewing you as a target, the more wars you have, the weaker you appear to AI, hence snowball effect of war declarations.

AI in Rome 2 is not dynamic, meaning if you make it not that agressive from start, it will ONLY get more and more docile as you grow in power, eventually having pretty much no AI declaring wars on player.

You can achieve a lot with diplomacy, especially from 1st turn, lots of player do strategy where they use initial cash just to build up diplomatic situation. Also dont give NAPs to everyone around, in Rome 2 every positive action towards X faction will give you penalty with Y faction.

Pick a side or they'll all be picking on you.