It's probably not considered secure because it's all one class of characters. It's a lot faster to bruteforce with "uppercase characters only" vs "uppercase, lo

It's probably not considered secure because it's all one class of characters. It's a lot faster to bruteforce with "uppercase characters only" vs "uppercase, lowercase, numbers, special characters". Now, if i would be trying to get as much userpasswords of a database as i can, i'd probably start with "lowercase only" and most likely will get the biggest amount of passwords. Afterwards try "lowercase + numbers", "case insensitive + numbers"..