Even doesn't pass the smell test, especially if one considers the data for cotton shopping bags versus plastic.

Per unit length of netting with the equivalent strength, cotton/hemp netting will weigh more, require more frequent replacement, require horrible preservatives which will leach into the marine environment, require more fossil fuels to till and fertilize the cotton, consume more freshwater in production, result in more top soil loss due to mono-cropping, need more pesticides, etc.

Direct plastic pollution in the ocean would be reduced yes, but at the cost of higher pollution and environmental degradation elsewhere.