The ability by websites to detect incognito cause real usability pains for users. (For example, certain news outlets refuse to show content when it detects that

The ability by websites to detect incognito cause real usability pains for users. (For example, certain news outlets refuse to show content when it detects that you're in incognito.) The mechanisms to detect incognito were/are unintended holes. Both FireFox and Chrome have been plugging them.