When I work with 8-bit images in Photoshop I never achieve to get smooth gradients when working with dark colors. I looks bad and it's a clear line between dark gray and black. My guess is that is because I work 8-bit files but is there any reason at all to not use 32-bit images on the web? Sure, they have a greater file size but is that the only reason? It doesn't have anything to do with web browsers and incompatibility with 32-bit images?
But when in Photoshop about every option you can choose with layers are grayed out when working with 32 bit and a great number of filters are grayed out when working with 8bit. So am I limited to 8bit if I want to use any creative built in functions in Photoshop?
Yes you limited to 8 bit, bcoz it refers to the color management,filters, effects and gradients will not allow you to apply because of referring to lower bits.Image mode will give you the options enabled in higher bits.