Because there was nothing else to compare it to at the time. It was the first viable hybrid, we agree on that. The part that I'm having a hard time explaining is that it was not hugely successful and not the motivation for all current EV's. It wasn't even a plug-in hybrid until 2012. That is 9 years AFTER Tesla.
Major manufactures did not attempt EVs until Tesla made a killing on them. Most of them did not even make serious attempts at hybrids until the mid 2000's.