Comment by maxgashkov

It's a long standing tradition from older forms of chat software (IRC, ICQ and so on) and yes, it seems endemic to Russian speakers for some reason. I always explained it to myself that it saves time and also by the fact that to type ":)" in Russian kb layout you have to press Shift+6, Shift+0 compared to Shift+;, Shift+0 in US layout which seems a bit more cumbersome.

Anyway, this is going away as most of the younger generation just uses emoji instead.