But by your definition every sexually reproducing individual is a hybrid.
There would probably be a number of hybrid loci in every individual. However, it tends to lose meaning in nature.
Hybrids are generally used in selective breeding. For instance, pure strains of corn are bred to produce hybrid vigor and higher crop yields. If you plant the seeds produced from hybrids, your results will not be good.
I don't doubt that, in most cases. But at some point in evolution there must be discontinuities in chromosome count. If these are always absolute barriers to reproduction, there is a problem.