I feel like the indicator would be helpful in threads for suggestions / bugs, where there is a clear thread author. But it would be sort of meaningless for manga / anime / topical threads, since the first person to post is kind of arbitrary.
Also, some random points of comparison:
Places with this feature:
[ul] [li] Reddit indicates the post submitter using [ S ] and a slightly brighter shade of blue
[li] YouTube indicates the video uploader by highlighting the name in blue
[li] Stack Overflow indicates the question asker by highlighting the name in grey
[li] Pixiv indicates the post author with a blue "author" tag next to the name[/ul]
Places without this feature:
[ul][li] Facebook comments
[li] Animesuki forums
[li] MAL forums
[li] MU forums
[li] phpBB-based forums
[li] AO3 comments
[li] DeviantArt comments
[li] GitHub issues[/ul]