I agree, though I've unfortunately seen several tests that suggest that they work. The immediate "Give us your email" is much more effective than requests that wait for a certain number of pages, trigger after a certain scroll amount, or wait until you've been on the site for a significant amount of time.

Of the people who see the pop up, the conversion rate is highest for those who see it immediately. And there's not a significant effect on bounce rates.

I have no idea why! I would never simply give my email address to an immediate pop up modal.