Others have pointed out the degradation issue, but you’re also assuming that all plastics are thermoplastics. They are not. There’s huge variation in chemical composition and material properties between different plastics, and most of them can’t be melted and reformed.
But then the problem isn’t with all plastics, it’s with certain plastics, and around 70% of global plastic production are concentrated around commodity plastics, all of which are thermoplastic. The greatest degradation issue occurs with biodegradable plastics, which is perceived as a good thing for them, though even biodegradable PLA has toxicity concerns.
Others have pointed out the degradation issue, but you’re also assuming that all plastics are thermoplastics. They are not. There’s huge variation in chemical composition and material properties between different plastics, and most of them can’t be melted and reformed.
But then the problem isn’t with all plastics, it’s with certain plastics, and around 70% of global plastic production are concentrated around commodity plastics, all of which are thermoplastic. The greatest degradation issue occurs with biodegradable plastics, which is perceived as a good thing for them, though even biodegradable PLA has toxicity concerns.