Agree with this, i had a similar issue in the past, and this was my fix
I do not know what killed my tomato plant. But it grew like a weed for around 3 months, getting to almost 5 feet tall.
I dug it out when I realized it was a lost cause.
The root system looked healthy but did not go down more than about 8 inches. The soil was not compacted and I also fertilized it.
Here is something I found humorous. I cut a branch off that plant that had a tomato on it that was about 1 inch in diameter.
It landed on a piece of shrubbery.
About a month went by.
I saw the cut off branch and the tomato was red.
I can not believe it had no rotted after a month.