Yes, they can be impersonal... yet like Autumn mentions, I remember when I first arrived and even a canned response was better than dead air... like no one even saw me...
As we all know, it can get busy here and threads can quickly drop to the third and forth pages... and some sitchs seem to demand a lot of attention at times, so some may miss those new members... it helps to pop their threads to the top so others might notice...
I used to try to welcome new members with more personal welcome posts and it helped me as it was my way to contribute in a meaningful way, when I didn't feel I had anything else to really contribute back...