The big thing is recycling doesn't work or is broken. Lots of stuff in theory can be recycled, and people see the logo and think they toss it in the recycling and all is good. But the issue is just because in theory something can be recycled and there is a process for it, most place don't do it. Such as plastics, only HDPE is highly recycled, the rest, basically not at all. But folks toss any plastic in the bin thinking it can be recycled.
Recycling is great for metals (steel, aluminum, copper), paper has a reasonable level of being recycled. The rest just ends up at a dump. For years the west sent the recyclables that couldn't be recycled, to places like China. Now they stopped taking it and all the recyclables are piling up.
It comes down to accepting that you have trash, you basically have 2 options, you put it in a landfill where it sits forever and causes who knows what long term impacts, leaks, emissions. Or you toss it in an incinerator, get rid of it, get some energy from it now, and just have to deal with some emissions now, but it's something you can control.
People like to hate the idea of an incinerator, but at the same time they probably don't know they very well live close to one and don't even notice it. Some are very large and right in urban centers, folks don't even notice.
Neither plastic or cardboard is great. Cardboard covered in fiberglass and other tapes and stickers is basically useless. Plastic has it's issues. Simple packaging is better, stuff that isn't high gloss inserts, multiple material etc. Plane brown boxes. Use less.
IKEA is good overall, they don't make a mess of their cardboard, it's clean for recycling. When you consider how much mass they are shipping, and how much smaller it is by being flat packed, it's a win. They have the thin foam separators, and sometimes the plastic wrap they use on parts. But folks don't want their stuff scratched or damaged either. Yeah you can have a lot of boxes when you complete assembling something from IKEA, but just picture what it would be like if it didn't come flat packed. Shipping a bookcase whole would be so much worse.