It should be mentioned that as far as I can tell pretty much no one is selling pure PLA filament. They all have additives, so who knows what the actual glass transition temperature is for any random given filament. This has been true for a while too. Pure PLA has some properly awful properties, among which is it having pretty much no elastic deformation. Any amount of force will introduce microscopic cracks. The various additives reduce these kinds of issues and are therefore not really optional.