Questions about my hibiscus

I bought 3 hibiscus last year, and two of them got about 8' tall, the other about 4' tall. They are all planted in the ground, not in pots.

In the late fall, all the leaves fell off, and I assumed it went dormant for the winter. I've been waiting this spring to see it put out new leaves, and the old wood has no signs of life. There is new growth coming from the lower 2-4" of some of the old stems. So, I tugged on one of the stems with no leaves, and it snapped into as if it were dead... actually, I then did the same thing to all of them, and they're all brittle and dead.
So, here's the questions.
Do they start all over each year? Will those little starts grow to the size plant I enjoyed last year (4' - 8' tall)? Should I have cut all those stems back in the fall?

Actually, these are my very first hibiscus to actually survive more than a year.

Are they tropical hibiscus or hardy hibiscus? If they're hardies (H. moscheutos) then they are supposed to die back like that and resprout from the base every year, so they should grow just as big and nice as they did last year (assuming you keep them happy of course!) If they're tropicals (H. rosa-sinensis), they are not supposed to die back over the winter, but in your zone they might since they're not going to be reliably hardy. But since they're not supposed to die back every year, they may take a little longer to recover and may not get as big as they were last year. If they are tropicals, you might be better off keeping them in pots and bringing them in somewhere warm for the winter.

Thank God for flashlights... I had to go look at the tags. Pjs and all.

The two that grew to 8', and have the most leaves at the base are hardy hibiscus. But the one that only got to 4', I see a little green on the lower stems, but no leaves yet... is a tropical hibiscus. So, that answers that question.

Thank you so much for clearing that up.

See how the tropical recovers this year--if it comes back quickly then you're probably OK leaving it in the ground, but if it's a bit slow to come back then you may want to consider keeping it in a pot instead and bringing it in for the winter. I am much happier with my tropicals since I got a greenhouse--they would typically survive the winter here but they would be so slow to come back the following year that it would sometimes be the middle of the summer before they'd be blooming again, but now that I keep them in the greenhouse some of them continue to bloom all winter even, and the rest are ready to go come spring.