When I say baby containers, I refer to products sold to hold your baby. There are many products like this sold because, let's face it, looking after a human who is 100% dependent on you is really tiring and sometimes you just need to be able to put your little one down and have both hands...and your body generally, free.
My first suggestion would always be to explore slings and babywearing to give you that hands free chance to still hold your baby close. However, for some, that is not what they can or want to do. And the alternative being to always lie baby flat on the floor on a playmat or in their safe sleep space may feel a bit unfair (as well as not helping with head shape development - more on that another time...). So, the money-making people heard you! They created a vast array of various containers to hold your little one for you. Some do just that alone but most now have many bells and whistles attached...some are electric, they sway and rock and play music, some have toys attached.
Most, are designed so your baby is on an incline, like in a car seat, optimal positioning for them to look around (to the extent they can see that far....).
So, what's the problem?
As is the case with car seats too, babies, whose neck muscles are still too weak to hold those big, adorable heads of theirs, are not safe left unattended in an inclined position. When you look at the label on a commonly used baby bouncer seat, you will see one of the warnings is to keep your baby in view at all times. This is so you can ensure baby's head is not dropping onto their chest and their airway is not being restricted. And yet, scary as it is, it is not always obvious, especially when your little one is very small (and very sleepy) just by looking, if their airway is ok. So, when using one of these, make sure you are watching and checking baby and minimising the time you leave them in this position.
A crying or unsettled baby is hard, and yes, swaying and rocking, and shhing are all great ways to calm your little one. However, I would not recommend relying on a bells-and-whistles robot chair to do this for you. The risk is just too high, especially if they then drift off to sleep and, understandably, you are less than inclined to disturb their slumber and move them somewhere safe and flat and risk waking them. It is much safer to risk disturbing their sleep and get them back onto a firm flat surface rather than leaving them (even if you are there watching).
Meanwhile, other baby containers, that may not be on an incline but hold your baby either upright, in a seated position, or standing (like in a walker or bouncer), are advised by the NHS to be limited to no more than 20 minutes at a time. This is because they restrict your baby's natural movements which help them to develop their gross motor skills, such as rolling, crawling and walking! Some are even advertised as being for babies that are far too young - for example, standing bouncers from 3 months old when they've just learnt to hold their own head! Yes, baby's bouncing around in a harness attached to the door, or careering around on 2 legs and multiple wheels is an adorable sight, however it is also not necessarily helping them to develop in the right way. Babies in these are often on their tip-toes and can find it harder to move away from this and learn to walk flat on their feet. Meanwhile, placing your non-sitting baby in a seated position can end up delaying the development of the strength they need to sit without the support.
So...in summary: I'm not saying you must never use these sorts of products or your baby will never develop! What I am saying, is don't see these as long-term spaces to hold your little one throughout the day. Yes, by all means, use a container after a period of babywearing or floor play, but also ensure there is plenty of time and opportunity throughout the day for your developing baby to become acquainted with their body and the space it holds, to build up the skills to roll and to crawl and to, before you know it, run round and round the living room while you're trying to put their coat on.
I offer a range of guidance for new parents, including tailored advice and hands on support.