I haven't clicked on the link but I would imagine that a lot of people (sadly) try and force their children's food into their mouths when using a spoon.
This will kind of override the child's natural 'stop' switch, so they are less likely to be able to assess when to stop eating when they get older.
that's kind of my theory anyway.
I do use a spoon to help my child eat yogurt and so on, at a year old - but when he doesn't want any more, I stop, and let him do whatever he is interested in.
I would never, ever force food into his mouth. But I have seen it happen a lot. I would even go as far as to say sometimes people are encouraged to try and get the baby to eat as much as possible before 'giving up', with concerns about their not being fed enough and losing weight being fairly strong especially in the minds of new parents.
Mine have all (three) existed largely on milk for the first couple of years at least, with very little food making its way in.
But I have a history of anorexia and a family who overeat, and really, I can't think of anything worse than being forced to eat. So perhaps I am too laid back about it.