Yes rant away.
I think a lot of it can be down to personality of child, yes you can try to encourage good sleep and it sounds as tho you are doing all you can.
Out of my five, ranging in age from 13 down to just 2yrs old.,
Ds1 white sleeper for three years, now as a teen he likes his sleep but still suffers from insomnia at times.
Ds2 not a great sleeper but better than ds1, by 18mths wish he was pretty good.
Ds3 similar to ds2.
Ds4 a miracle baby who just slept amazingly from birth and still does at age four, he sucks his thumb, was sucking it at the 20wk scan and sucked it from birth and I ask pretty sure that ability to self sooth through thumb sucking is went he has always slept so well.
Dd just two yes old and pretty good, not as bad as ds2 and ds3, not as good as ds4. She has had her moments and some crap phases but is OK.
I would not to cc, but we were consistent with bedtime routine etc and all the stuff that is meant to help encourage sleep.
I have to say it is biologically normal for babies to sleep with their mums and bfeed in the night. Sleeping in cots and especially in another room is a very western phenomena from the last 100yrs, not something babies ate designed to do biologically.