Are people really that lazy? They can't be bothered to change their notification settings so they just post "subscribed" everywhere. It does get kinda annoying...
You missed the entire point, there is no "setting" to change to accomplish the same thing that posting in a thread does. They want it to be added to a watchlist like "Show new replies to your posts
", notifications only send you emails which is largely useless.
This has been covered a couple times in this thread already, but guess you're too busy posting in threads to read them.
Even says it in the OP
It seems that people use these "subscribe" one-liners rather than click notify because threads flagged via the latter mechanism don't show up under "Show new replies to your post."