Take a look at Veritasium's perspective on this issue [1]. Veritasium reflects on clickbait thumbnails from the content producer perspective, and balances that against the motivation behind YouTube's algorithms. His final conclusion is that cilckbait isn't all bad, and that it serves an important purpose for both viewers and content creators. His classification of clickbait into different types is also fascinating.
[1] https://www.youtube.com/watch?v=S2xHZPH5Sng