Older rubber ones eventually oxidize and get sticky. They're older rubber plunger type was also harder to push / pull in or out for storage when the aeropress is dry (like for storage).
These are nicer / easier and still create a good seal when pushing the coffee through. But I find it's a little looser fitting on the plunger base part it's attached to so when rinsing water seems to get under there a bit, so you get a bit more dripping from it than I was expecting. Not too big of a deal just make sure you shake it out.