Not that they are necessarily bad, but can be a source of weak connections that fail to pass the feed on to the next outlet. The new outlets only allow #14 wire to be stabbed into them. I find that making up my connection with wire nuts allows me to tie all neutrals, hot and of course grounds in such a way that all I have to push back into the box with the outlet are those 3 wires as the connections are already tucked in. Doing that with 3 neutrals, 3 hots can be harder and put a strain on the outlet and the connections going into it. Its also why I always try to bring my wires in from the same orientation, that is, top or bottom of the box. One other tip is to bring your line or power in at the same spot in each box.