tbf it wouldn't be a bad signal for search engines that can understand forum markup.

A boon for search is knowing intent and know who wrote something certainly helps in that regard, if a strong enough signal of course. Without knowing who intends what, you basically rely on the topic and words.

From my time in the dying days of Usenet, I can remember there were compact codes so you could fit as much about yourself into your signature as possible. Something like the old dating ad codes, e.g. GSoH = Good Sense of Humour, but more geeky.