I don’t know if this applies to all the 40 countries Tupperware is selling to, but at least here in Germany, the need to „eintuppern“ (to put something into a Tupperware container) has massively decreased. Up until the 90s it was much more common to cook in abundance e.g. on the weekend and store the leftovers to eaten throughout the week or even deep frozen. These days it is much more common to cook only what you intend to eat right away.

At the same time, the trend went away from buying huge packs of stuff that need to be put in a container to not go stale, towards buying smaller-sized packages, for a multitude of reasons.