EWW is a little too austere for general browsing IMO, but it's more than useful enough to make up for it in a few situations.
1. Copying large sections of text. Say I'm reading a tutorial or something with code blocks, and I want to run them. If I'm in a "real" browser, I have to click and drag to copy the text to my editor, and clicking and dragging sucks. Instead, I can open the page in EWW, then set the mark and search (C-SPC and C-s) for a more pleasant copying experience. (I realize this sounds petty, but it makes for a little less hassle in my life.)
1. Copying large sections of text. Say I'm reading a tutorial or something with code blocks, and I want to run them. If I'm in a "real" browser, I have to click and drag to copy the text to my editor, and clicking and dragging sucks. Instead, I can open the page in EWW, then set the mark and search (C-SPC and C-s) for a more pleasant copying experience. (I realize this sounds petty, but it makes for a little less hassle in my life.)
2. One-off scraping tasks. This is a powerful technique, and it's my go-to example in a "but can your editor do this" discussion. For details, see https://nickdrozd.github.io/2018/10/17/web-scraping.html