I think someone who loses an only cat needs to be cautious
I had a Siamese girl for 14 years, and when she died I got, after a few months, a male kitten, but I found it very difficult to bond with him, because I really wanted, and needed, the companionship of an older cat, which I had had for so long, and missed so much
but now I have 3 adult cats I would not hesitate to take on a kitten if I lost one, as I would not see it as a replacement, any more than the other two survivors would be replacements