This. You’re not causing permanent damage to a child by letting them sleep in your bed. You don’t need an academic answer on what research says about this.
I don’t like it because my kids kick and move around, so I don’t want them to sleep in my bed.
The main advice for parenting should always be “you do you”.
You get better at something by learning and practising. Sounds so dumb and simplistic and obvious, but it amazes me how difficult people find it to truly accept and internalise this.
Shit at cooking? You can improve.
Shit at talking? You can improve.
Shit as a friend/spouse/parent? You can improve.
Shit at reining in your emotions? You can improve.
You could literally practice to be a funnier person if you wanted.
I guess this is now popularised as “growth mindset”.