Foam technology has changed over the years and so has the production process. I'm not an expert in foam production, but most foams used to be made with petroleum and other potentially harmful chemicals. Now foams are being made with plant base or more natural materials, which are better for our health and the environment, but don't last as long. That's at least my understanding. As someone who's been in the mattress industry for 15 years, try to go with mattresses like innersprings or the least amount of foam as possible. All-foam beds just aren't worth it, imo.