In my personal experience, the only time when the top reply and the accepted answer differ is when the answer has become obsolete over time.
E.g.
Q: "How do I do X in JS?" in 2010
A1 (100 votes, accepted): "Use jQuery function jX()" (2011)
A2 (300 votes): "Since 2015, the standard function jX2() is supported in all major browsers. [link to caniuse.com]" (2016)
