Some of those I saw years ago were raised from young and smaller sizes, and yes most were males. I saw one that left me thinking that it could have been female, but at that time and to this day I dont know if he or she was one specifically.
I think that you dont see that many big ones today because so many keepers lose interest and sell or trade them off after a few years if they do keep them that long. When the people who buy or trade to get large albigs and waters get them, its a novelty and the animal suffers.
One factor may be the cage size and area they need, the animal suffers for it when the reality sets in on the owner. One factor may be the loss of interest in continuing to feed such a monster after time passes, although they eat so much less as an adult.
Around the time I was raising Sobek from a hatchling there were a few of her siblings in a few keepers care on this forum, within a year or 2 I dont think any of them were still in their orginal owners care, and none were 5ft by that time. I knew of one guy who had 3 of them for about 3 years, the one male was around 5-5.5ft but he sold or traded them at some time to focus on dwarf species, beardies, and argus of which he had good sucess with.
I think part of what I did right was I kept fewer reptiles in her first year. Part of it was continuing with larger and larger cages. Also I swear by 24/7 basking lights with low wattages, high basking temps, good temp gradients, and the use of dirt for a substrate.
I think it would take way too long to specify everything I did right with her.
I read a few articles over the years where whitethroats studied in Kruger national park were averaging 6ft plus for males, and 5-5.5ft for females. There were tons upon tons of them to study, I dont know how long they were studied, and it didnt mention how large they got as a maximum. My guess would be nature being so rough on them limits their size. Also being large lizards, but not large enough to set records they are not so noticed by those who look for the biggest examples or species so no one seems to know how big they can get.
Mark Bayless had a female that was 6ft 2 inches, but I dont know of any close otherwise, and he didnt know of any either.