This was indeed the case, but I recall that even in late 00s there was already a spam problem with this mechanism. OTOH over the years (especially during covid

This was indeed the case, but I recall that even in late 00s there was already a spam problem with this mechanism. OTOH over the years (especially during covid lockdowns) I got a few messages from strangers on FB Messenger and Snapchat, and usually replied to them, and it was fun. However, it was always caused by some FB post/comment or Snapchat story that I posted before. Still, I guess if you have enough bored people, they will find a way to socialize no matter the medium.