No, that's not true. Although the manufacture and disposal of plastic is detrimental to the environment, a large amount of plastic packaging is truly lightweight. A great deal of plastic packaging is therefore awarded the rating "Very light" in the important factor of "Weight", which means that the packaging consumes fewer resources over the entire value chain and thus has a less harmful effect on the environment.
Furthermore, a lot of plastic packaging already contains a large amount of recycled materials (e.g. PET drinks bottles can be made with up to 100% recycled materials) and some can be recycled easily (e.g. the recycling rate for PET drinks bottles is greater than 80%). In three of the four M-Check factors, some plastic packaging frequently performs very well.
An important reminder with respect to plastic packaging (as well as for other packaging): please always dispose of it correctly! Packaging should never find its way into the environment.