As I said the only real problem is AI not being great at handling it.
It's a pretty fucking huge one for a central feature on a game that 99% of players have never touched the multiplayer on and the developers have come no closer to fixing in two games now.
Even standard difficulty AI in Civ IV could be dangerous with it. Civ V and VI degenerate gameplay is sitting one archer unit in a city and being able to mow down endless hordes of attackers (even stone age tribes in NuCiv seem capable of Omaha Beach-esque 10-to-1 defences while only having a single unit in important cities was incredibly dicey unless you have the Protective trait or can get some early walls up). Spreading your forces thin like that in Civ IV could be very dangerous if you were surrounded by multiple hostile powers with even defensive playthroughs for large empires often encouraging a large mobile reserve to be able to counter-attack enemy stacks or at least try buy some time for you to get your production on a war-footing.
Civ IV fighting led to a lot of fun and desperate moments and also encouraged sensible precautions like keeping a good eye on your enemy and encouraging a best defence is a good offence attitude. I don't have a single fun memory of a war in the last two Civs they were boring and tedious with a timid and incompetent AI. No "holy shit" moments where you've got to scramble like a madman, use delaying tactics and even possibly sacrifice a city or two against enemy invasions if you're not properly prepared.