downvoting because it’s not really true what you said. sure there’s always exceptions in biology that don’t fit into the species concept, but i dare say for lots of living beings, including practically all eukaryotic organisms, with very few exceptions, it’s a good categorization scheme.

the exceptions you mentioned (asexual reproduction; edge cases where interbreeding is difficult but not impossible) are the exception, not the rule. that doesn’t make the rule meaningless though.