> but you can also use a liner.
Now your box of liners consumes the space that your cake tin would, and you haven't changed anything.
Unless you buy a liner as part of the ingredient list and toss it when your done. Sure, it's less than optimal if your making a lot of cakes, but if you just make 1 or 2 per year for birthdays then it's really not a big deal.
I have watched a professional baker make several high end cakes and she used very few specialized tools. The icing/Pastry bag was really the only non standard cooking item.
Remember, people want to sell you stuff. That does not make stuff necessary.