As an aside, I can't believe Dinosaur Comics is still active. I looked it up and it started over 20 years ago in 2003. 4176 comic strips using the exact same artwork almost without exception.

What webcomics really need is not a search engine but an index of "most viewed" strips for each one. For longrunning webcomics the latest strips are often not really interesting for new readers, but there are a few (or more than a few) standout strips from the past that are really funny and could draw people in, only you can't easily find them just from the webcomic's home page.