Comparing 16 PSI Radiator Cap to Carbonated Soda Can Pressures

many years ago one of those great old radiator shops that you can hardly find anymore suggested that I use a 7 lb cap on a recored radiator. I did it and never had a lick of problem with it. I've used 7 lb caps ever since. I guess from the info above the boiling point of the contents is lower because of it, but again, never had a lick of problem using them. I've never understood if there was a reason to put the extra strain on the cooling system with a 16 lb cap - maybe someone can educate me?