Not necessarily for groceries, but otherwise yeah.
There are some things that I need to permanently store in the car, and using backseats for that essentially makes them unusable for their primary purpose (hosting humans). I am not even talking about the bewilderingly very common in the US "I use my car trunk as a small storage unit" scenario. I am talking about storing things like backup tire, first-aid kit, electric tire pump+sealant combo (in case i get a small puncture in my tire, so that I can patch it up and get to the nearest parking lot/service center or home), a charging cable+adapters (in case you drive an EV), a change of clothes, a roll of paper towels, and maybe a change of clothing. Mind you, even with those things in mind, they won't take up a lot of space at all, and trunk is still very usable for groceries and other stuff.
The main issue is that without trunk at all, even a very small subset of bare essential things from that list (first-aid kit and a tire pump) essentially create a problem where they are always occupying the backseat area of the car, which makes it problematic for humans to use.