Plastic is kinda like a chemical that can't decompose in soil and maybe reacts to other chemicals. Anyways, maybe its because glass does not dissolve in the chemical. Plastic kind of does a little. Well at least something like dissolve.
Some beakers require an applied bunsen burner. Maybe a more practical device. Easier to clean and sanitize by steam if needed. (Some acids (hydrofluoric) eat through glass, so you might need a plastic or stainless steel also.)