Do you mean why didn’t most cars on the road become hybrid before electric-only came into being?
Simple answer is because we didn’t have to wait that long. Hybrid was a crutch for a lack of scale for making electric batteries in bulk as well as for missing infrastructure to charge all-electrics.
It’s like asking why we don’t dim a lamp before turning it off or let food cool off on the counter before putting it in the refrigerator. It does more harm than good to keep producing hybrid vehicles vs all-electrics.
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