A lot of the above, actually.
Maybe a visual would help...I made this using MAX 2013: https://www.youtube.com/watch?v=XfcWbxqqpJA

The full thing is 28 minutes long and doing okay-ish on the film festival circuit.
But the problem I had was that the toon-shader could not react to the color of lights, treating all lights as white.
I had one scene that took place at dawn, and it required adding an RGB Tint to absolutely every material in the scene:

I considered trying to do that in post, but I knew it wouldn't come out quite right.
And even then, if I had lights of multiple colors, I couldn't make it work at all.
After that project was completed, I switched to MAX 2023, and it seems like everything has changed, especially with the Arnold renderer; I really miss MentalRay. And Scanline is soooooooo slow, prohibitively so.
The problem I'm having in 2023 is similar: the hard edges of the shadows seem only possible using a tone map, which then also eliminates any reaction to the color of a light.
This is the best I can get:

...and it requires messing around with specular and sheen, which I do not trust to behave themselves under all lighting conditions; there seems to be a tendency for the highlight to go way overboard if a light is too bright, turning pure white, and it looks like the character's skin is made of metal or polished plastic.
The legacy Ink'n'Paint material may not have been perfect (especially when inking), but I had so much more control over how the material would react to lighting, light-color notwithstanding.
The big problems with Ink'n'Paint were the colored-lights problem and that Ink'n'Paint doesn't support translucency; to make helmet visors and spaceship canopies required some serious gymnastics involving Composite materials (and sometimes objects which were behind the transparent ones would render black, which required even more gymnastics to fix, mostly involving slightly smaller replicas of the objects using completely transparent Standard materials, which worked like the CeThru plugin; it took so much juggling to get it all working properly).
Without the tone map, models barely look toon-shaded in 2023; mostly only the inking indicates it. The shadows are very soft, without the hard edges I'm after.
Another problem I'm having is making things glow.
Spaceship engines, for example:

MAX 2023 seems very resistant to producing this effect; it seems to require messing with environment settings, which is not what I want at all; I just want to say, "This material produces a bloom effect; it's this color, this bright, and it's this big relative to the surface it's on". Simple, simple, no fuss. I'm after a special effect, not a practical effect, if you take my meaning, but Arnold seems to want to do absolutely everything as practical effects, products of the environment, rather than allowing the user the ability to break the photo-realness of the image to produce something specific which may never exist in a "real" environment.
It would be the same if I was trying to make a lightsaber's blade; I see so many people asking how to do that when I do a Google search, and basically nobody succeeding. I could do it in MentalRay in five minutes, tops, but not in Arnold, apparently.
Using Lens Effects doesn't work because the glow stays the same size in pixels, not volume, so a distant object would have this huge-but-dim halo around it). And Lens Effects also can't be saved, do not transfer from scene to scene, so importing objects requires manually re-entering all of the effect's parameters every time.
I was able to do what I needed with the "Glow" map in MentalRay; that did exactly what I wanted, and the only problem with it was that the glow was not reproduced on reflective surfaces. I need something that works the same way.