Children need to learn to eat and it is slow and difficult work. At 6 months or so the food they get by spoon or hand may or may not serve any nutritional purpose, but is part of that learning process for them (and for the adults trying to get it into them.)
As time goes past between that first mouthful and say the one-year mark so much happens:
- the baby learns how to open for the spoon, take in a mouthful, and swallow it instead of spitting it out
- the baby learns how to manipulate soft food (move it around inside the mouth with the tongue) so it can be chewed, to chew it, and to swallow it
- the baby learns how to communicate "I like that! more!" and "I don't like that!"
- the baby learns how to get across to you that they don't want something in the future, or that something is their favourite
- the baby takes some control by picking up certain kinds of foods (a cooked pea, a little cereal piece, a little cube of a soft fruit) and feeding it to themselves
- the baby learns that different food have different textures and tastes and is exposed to a variety of them
- the baby starts to develop preferences and realize she can choose some of what happens to her such as what she eats or at least what she swallows
- you learn how to spoonfeed (it's a skill) and how to interpret those early attempts at communication
- you teach the baby how to be part of the team effort of getting food into them; you will use these skills when they need to co-operate with getting dressed, brushing long hair, and thousands of other activities
- you teach the baby your values, for better or worse: I remember a grandparent who said after every spoonful that went into my oldest some sort of value judgement like "mmm! yummy! sweet! good girl!" or "strong taste to make you strong!"
In contrast if you thicken milk with cereal or pureed vegetables the only need you are meeting is nutritional. 50 years ago doctors would suggest this for babies that weren't sleeping well. That might have some value, but it's not a long term strategy to stick with till one year of age.
Accept that this is one of those hard things babies and their parents are going to learn. Don't try to start it too early - that makes it even harder - but don't try to skip it entirely. Perhaps you want to minimize the length of the "spooning mush into the mouth" phases, but do so by getting the baby self-feeding (not with a spoon, with things she can pick up) not by sticking with the bottle.
