1) You are creating negative sleep associations
If they sleep in the wrap or sling they will never learn to sleep anywhere else
The theory about sleep associations is not new. You hear it all over the place if you rock to sleep / feed to sleep / wear to sleep then the theory goes that your baby will never learn to go to sleep any other way, and may even have trouble going through sleep cycles at night. But the truth is that it doesn't matter how you get your baby to sleep, in their own sweet time they will start putting themselves to sleep. Sometimes that time is a bit too long for a parents liking and we might choose to give them a bit of a nudge along. But there is no rhyme or reason to it. My first didn't go to sleep on her own reliably until she was over a year old, my second by the time she was six weeks. It might not feel like it at the time, but you will not be feeding/patting/rocking/wearing your 10 year old to get them to go to sleep.
2) Babies should learn to sleep on their own
You are doing a disservice if they don't learn to go to sleep on their own.
The idea that babies should sleep on their own is a rather new one. Adults often have trouble sleeping in a bed alone, or need to have a hot drink, read a book or any manner of other routines to help them get to sleep. So the idea that a baby should be able to go to sleep without company, comfort or help is pretty unrealistic. It might be tempting to think that once a baby goes to sleep on their own, they will sleep for longer and will be better rested and in the long run better off. But it's no guarantee. My little one puts herself to sleep and regularly (very regularly) cat naps through the day anyway.
3) Babywearing creates 'clingy' babies
The idea that babywearing will somehow stunt the development of independence and resilience.
In the 1950s baby experts thought that resilience was created by parental detachment. However, it is now known that a secure attachment leads to independence, emotional availablility, better coping skills, improved moral development, reduced stress and improved academic performance.