Did you look at the tomato-slicing video at the bottom of the answer? Even if the many, many upvotes came because of the first part of the answer, the video validated the answer, made it worth keeping, and elevated it far above the two deleted answers.
The OP asked for a simple test, and the answer provided a simple, inexpensive test with a video demonstrating the test. The only hard part for most of the year would be finding a ripe tomato; slicing a supermarket tomato would prove little.
In response to the comment of @Gabriel C:
Yes, but then if you get rid of the useless paragraph and image, the
answer becomes a one-line answer based on an outside link video, which
again isn't what is usually considered a good answer.
Several of the answers provided less evidence than the helpful video. If this answer is to be deleted, those should be also. Moreover, I'd rather test the knife on a ripe tomato and keep the knife away from my hair, or a finger, or even a fingernail. Actually, the video proved to me that I don't want that knife in my kitchen -- too sharp!