I find these threads so weird (BTW yes I do have 3 kids though 
)
It's not just this topic, it's also
Everyone on MN earns over 100k (5% UK population)
Everyone on MN has had a contraceptive failure (About 1-2% per year of use)
Everyone on MN has ADHD/autism/a child/partner with one of those things (between 1-5% of population)
Everyone on MN breastfeeds for several years (About 1% UK population BF at 12 months)
MN has an enormous number of posters. They reckon 8 million a month or something with 20,000 actual posts a day. So even 1% is 80,000 MNers. Or 1% of the posts per day is 200 posts. 200 posts every single day made by any person with an experience that only 1% of the population have.
Most MNers have children, and among people who have children it's not THAT unusual to have 3. From ONS:
Of all families with dependent children, families with one child made up 44% (3.6 million) in 2022. Families with two children made up 41% (3.4 million), and families with three or more children made up 15% (1.2 million).
So there you go - about 15% of all families with children have 3 or more. Or 6.3% of UK households are families with 3+ dependent children (assume MN figure is higher, because most MN users are mums of dependent children.)
That's a lot of MNers.
The best thing about MN IMO is that you do find the one, two, five, six percenters, and a lot of them. You find the less than one percenters too. One of my children has a condition that affects about 1 in 1000 births, but I've been able to find advice/experiences of it here, because there are so many thousands of MNers, you put the right terms in your title, that's 8 million pairs of eyes potentially reading it. Just on pure statistics, 8,000 of those are likely to have had direct experience of what I'm asking about. In fact, more than 8,000 because a lot of MNers have more than one child and every MNer knows people other than their own children. Of course not all of the 8,000,000 are here for the whole month, but even if you divide it by 30 (days) and then again by 24 (hours) if it happens to stay in active for about an hour, that's maybe 11,000 people seeing my thread title, of which 11 may well have experience and choose to click on the thread, and that's just when I post it the first time, if someone then searches and bumps it again six months later that's another 11,000 people.
If you think that something that affects somewhere between 6-15% of MNers is a small number then you either vastly underestimate the number of MN users or you completely misunderstand percentages. Something can be a minority and declining, but still be a large number.