Google controls the APIs that extension writers can use. They are currently using that control to impose limits on what adblocker extensions can do. [1][2]
You could download the Chromium source and patch it to change the extensions APIs (or better, just use Firefox), but the majority of users won't do this, and extension writers aren't going to make a version for a patched Chromium browser unless it has significant market share and support.
You could always provide an extension that loads itself as a .dll/.so. I don't see much difference in friction between adding an extension through google's website vs. download setup.exe from somewhere. Of course like you say, using less user-hostile software is preferable.
Such extensions would be trivially easy for Google to break with Chrome updates. You also cannot distribute an extension like that through any of the usual extension stores.
Better to just use a browser that actually respects its users.
That might work for highly tech savvy people, but that's a very small minority of users. Google will still make ad blocking near-impossible for 99.99% of its users.