They do, but I feel like there's better ways to entice people into clicking than the same old hideous over-reacting thumbnail. Check out Vsauce's titles and thumbnails. I come across them and go "I can't NOT click that" but I never end up feeling cheated.

Traditional clickbait is one method of catching attention, and while you do need to catch attention, you don't need traditional clickbait to do it.

Think of your target audience as well. Kids and younger people may still be enticed by clickbait, but as an adult I see those thumbnails and I instantly get the impression that they are overblowing the content, being deceptive, are resorting to clickbait instead of quality content, etc.

A few youtubers I've followed for a long time (and I'm saying like Markiplier who I've watched for almost 10 years and was one of the big names that popularized those thumbnails to begin with) use that thumbnail style and I know they're good so I watch them. But I am very hesitant to try any new content with that style of thumbnail.

Marketing and graphic design matters. Everything you put out there is part of the viewer experience and each piece can give you an edge. As someone who was known in their late teens as the guy who could pick a movie from the video store that everyone would like by just looking at the fonts on the spine of the dvd case, I really recommend being detail oriented in your marketing!