[minimaxir]

Self-promotion aside, you should disclose that you are ex-Reddit.

[phyzome]

To be fair, kickme444 was pretty well-known as a reddit employee! (But explicit disclosure is good too.)

[pferde]

Some of us rarely ever look at the username behind (above) a comment. I personally just don't care, if the content is interesting.

And even if I did, there is just too many users, across various discussion sites, to keep all the pseudonyms and their comment history in one's head.