> why not just jump straight to electric motors

Because they can't satisfy every need just yet. Imagine we still have horses even with engines being around for more than a century. And adapting to a newer IC tech might actually be cheaper and easier than redesigning for EV tech. Manufacturers already have the experience, logistics chains, much of the designs, etc.

Some transitions are never complete because sometimes there's no "one size fits all" option for the manufacturer or the consumer.