Modifying Stardew Valley through SMAPI (Stardew Modding API) allows for multiple mod folders if you create specialized links, and so it would be nice if Curseforge also did this.
As an example, one of my desktop links redirects like this - "C:\Program Files (x86)\Steam\steamapps\common\Stardew Valley\StardewModdingAPI.exe" --mods-path "Mods ( Basic )"
There are many mods that only change the cosmetic appearance of your farm. So you could have a Witchy aesthetic farm, or a Victorian farm, but you have to have separate folders. Or there are different versions of the farm map that you can use, but they replace a vanilla map. Or there are mods that allow for more farm animal variety if that's what you want. But all of these mods replace vanilla files, so you can't have them installed at the same time.
There are also tons of mods that function perfectly well in singleplayer, but won't work at all in multiplayer, and crash the game if installed. I have some mods I can use with a friend who only plays vanilla Stardew, but other mods make the game impossible for them to play vanilla while I play modded.
I personally have 13 mod configurations on my PC and was looking to switch to Curseforge for the automatically updating mods feature, but without the ability to create differing modpacks, I cannot use Curseforge for Stardew Valley.