I don't intentionally standardize nor do I intentionally proliferate calibers. Over time I've gained and lost interest in shooting particular calibers for recreation, because the thrill is gone, that's all.
As much as I wanted to keep my reloading
gear to a minimum, it's
components I like being able to keep to a minimum--but market conditions have solved that problem for me.
I feel very fortunate that the firearm/caliber choices I've made have resulted in a nice re-use of some gear and components: 40SW and 10mm are two calibers I chose because I like them, and they happen to use much of the same reloading and casting equipment. Likewise with 45 Auto and my recently attraction to 45 Win Mag, the two sharing everything but powder. The two odd men out for now are .22LR, which I have zero interest in shooting and don't even enjoy a little bit when I do, and 44 Mag, which I can't currently get enough of.
I'm not really interested in collecting a variety of firearms, definitely not the same firearm in multiple calibers, and I expect the next gun I buy (not counting the one I bought yesterday) will very likely be in a caliber I already have. For me, I've proliferated enough.
Limiting to what I've already expanded to is a consideration--not a rule but a consideration of available space and expenditure of money on what is nothing more than a great hobby for me.
I had to have 45 Win Mag though. I think everyone enjoys something exotic, and I can neither afford nor tolerate women or cars that fit into that category.
Just as an aside, my father's definition of 'standard' was pretty simple: if it was an adopted US military caliber of the 20th century, it was standard. If it was a civilian-only caliber, it was a 'bastard' caliber. Anything that any other military weapon was chambered in (except anything produced by Russians, the French, Japanese, Italians or Chinese) was potentially acceptable, even if not standard. Things were fairly black-or-white for Dad, rest his soul.