YOU may well understand (and it is clear that you do) but you are in a small percentage of users (and there's always the day-zero attacks on the publishers of the plugin).
As ever, it is a balance between convenience and risk, which sums up the overall thrust of this thread. People's perception of risk varies, I've sold my soul to Google because I feel at least I understand how they will resell it, and I'm happy with the bargain. Facebook, Instagram, Yahoo etc much less so, but my real world options are severely limited by the interactions with my online community.