Is there a reason not to use <=> (null safe equals operator) in mysql instead of =?

Question

MySQL provides a nice operator <=> that works with comparisons that could contain a null such as null <=> null or null <=> 5

Answer 1

Yes.

This must be because relational databases use the theory of three-valued logic (TRUE, NULL, FALSE).

And the three-valued logic must work so because it must be internally consistent.

It follows from the rules of mathematics.

Comparisons with NULL and the three-valued logic