Wobbles, the thing about the car seat is that long periods of time in a car seat can cause problems for baby https://www.drgreene.org/body.cfm?id=21&action=detail&ref=666
Therefore it is recommended that abby isn't kept in them for long periods of time. Th reason why car seats are still sold is because the benefits outweight the risk but travel systems come under fire as you tend to get those who leave baby in the car seat when they get to town. go round town, do shopping etc and then back in the car so they are not getting a chance to lie flat. If used properl;y and sensibly then there is no problem, I still have my travel system and will use it if needed but it is just those people who always have them in the car seat.