The only reason I know/knew is because I googled it way back when, ha!

IIRC, it had something to do with how the software formatted comments. If you just used regular spaces to try and line the triangles up, it wouldn't work, because the formatting would ignore any spaces at the beginning of the comment. So you had to use a different kind of invisible character, one it wouldn't ignore and get rid of, by using an alt key + number code that's slipping my mind because I'm not in front of a keyboard to use the ol' muscle memory.
(Although I rarely ever actually posted or commented. I took 'lurk moar' very seriously.)

A lot like how on here or Reddit when people try to do the shruggy guy ¯\_(ツ)_/¯ but because of the way the formatting works they get ¯_(ツ)_/¯ since they don't know enough to figure out how to make it display the way they want

.... I'm sleep deprived, can you tell? Lmao