That's the exactly same thing I said: you need to be on H1b (or other non-immigrant visa but allows dual-intention, for example L1) and wait for maybe years or decades (based on your birth country) to get that.
There is no mention of H-1B at all on the State Department page I linked you. Where are you getting this from? Sure some H-1B holders manage to later acquire an E visa, but nowhere is it stated to be a prerequisite. Exceptional individuals don't even need a US sponsor to apply.
Sure H1b is not a prerequisite technically. But say you are the employer, you want to sponsor this Indian person's E2 visa, but you need to wait for 11 years before they actually get the visa you sponsored and start to work for you. Now tell me how is H1b not a prerequisite in reality?
If it takes that long it's because the category you're in is heavily over-subscribed and at a relatively low skill level. Using H-1B to do an end run around that is common, but to call it a prerequisite is dishonest. Our immigration system has limits because we believe it is in our citizen's interest. This means not every foreign worker that wants to immigrate is going to get to. US law gives preference to exceptional individuals, because our law is for the benefit of our citizens and corporations, not foreign nationals.
Here's the current queue size: https://travel.state.gov/content/travel/en/legal/visa-law0/v.... For immigrants born in mainland China, E2's current queue is 4.5 years, for immigrants born in India E2's current queue is 11 years.