I really don't understand why any technically literate person would be impressed by the "!bang" stuff on DDG. You know your browser already provides this feature, right? Just configure some custom search keywords in your search settings. What does DDG offer that's better than this?
They already set them up for a ton of sites, though, and often you can guess your way to a bang on the first try. I have only looked at the actual list once or twice. Plus it seems to match the closest one in cases of using one that doesn't exist. I can also go to a machine that isn't my own and take advantage of them there right away. I heavily use the quickmarks in qutebrowser, but also the ddg bangs. I just hit O for open in new tab and can put in a bang right there.
I might not be impressed, but as I get older, I skew toward out of the box experience over configuration. I rather learn, and then apply that knowledge everywhere the thing is used, than configure, and lug my configuration around. Therefore, I value an opinionated feature like the bangs in DDG, even though as a professional, I know that there are many alternatives to it. If I know how to do it with DDG, I can use it everywhere I load DDG: my personal computer, my work computer, my phone's browser, my phone's other browser, the browser in the VM, the browser in the VM in the cloud, on the freshly installed computer with its default settings, everywhere.
Exactly. You can't except by setting DDG as the default search engine. Chrome, Brave, and FF for iOS also don't directly support this sort of feature either.
They proxy the !bang things so that whoever provides the search gets less info about who you are. Less isn't nothing, but it is still better than your browser can do without the proxy.