There are compelling reasons why a 7 year old should not be breastfed. I have mentioned this in my post that replied to, so I can only assume you choose to ignore them.
Comfort through suckling is what an infant does, because she has no other means to cope. A 7 year old should be well on her way to learning other coping skills that she is more than capable of using. As a parent, it is your responsibility to help your child grow and learn the appropriate skills of her age, and not enable her to get stuck in the stage of oral gratification.
"Nobody said it's the only way they could get comfort"
If she can be comforted by a hug and a kiss after a fall, for example, why should "comfort by breast" be used at all?
If your daughter is distressed because she didn't do well at school that day, you should be talking to her about it, helping her cope with a bad day and giving her courage for the next one. NOT giving her a breast to suck on.
We can do this all day, but the fact is that a 7 year old does not NEED to breastfeed. Not for nutrition, not for comfort, and not for immunity. At this age, she is physically and mentally able to move on to other, age-appropriate means of emotional and physical sustenance.
What remains for "justification" is "because she wants to" and that is never a good enough reason to stay stuck in infancy. We don't let our children go on drinking water from a bottle, go to sleep sucking on a dummy, eat through the night, and poo in a nappy, or breastfeed at the age of 7 even though that would probably be what they want to do if we let them. This is because They Are No Longer Babies.
There is a natural progression of nutrition, emotional sustenance, thinking and acting as a baby grows and becomes a pre-pubescent girl. It is your responsibility as a parent to help this process and guide your child along it, not hinder it by letting your child get stuck in ways of an infant.