Reason #1

"You can use a knife to kill someone, or you can use a knife to cut vegetables." Thich Nhat Hanh

Because you cannot cut tomato paste with a knife, it is not a vegetable.

I understand tomato paste has nutrients in it, and it should be given credit for just that. But that's it. It can go in a different category; maybe one that is called processed food that is made from a vegetable.

There are vegetables and then there are processed foods that are turned into a puree and slabbed on a crust and slathered with cheese loaded with fat and other processed junk.

SInce you can't cut the paste with a knife, it's not a vegetable. The knife is hence useless and is now available to kill someone.
Tsk tsk.