The adblocking/script-blocking capabilities (described in #9 and #10 in their FAQ: https://qutebrowser.org/doc/faq.html) are extremely weak and inconvenient (and their claim about the negative impact of adblocking is outright false).

Those are probably the two most important capabilities for security, so the lack of them definitely means I'd never want to use it for general browsing. I'd much rather deal with weaker keybinds than sacrifice that much on the security and privacy side.