Why should planting genetically modified crops be isolated from traditional agricultural crops? Thank you.

hybrid breeding may cause genetic pollution. For example, some crops have herbicide-resistant genes, and if they are not isolated, the herbicide-resistant genes may cross pollen with some weeds of the same family to produce herbicide-resistant weeds, and it will not work if they are used again in the future. This is just a situation, there are some other reasons, I hope to adopt ~