That is: why just one password field?
Verify input behavior has been around long enough for the UX of it to be studied and the results are basically that it's a pointless field. Statistically the vast majority of people actually get their password correct the first time and actually typo it the second time in the verify input field. This creates doubt and the end result is users have to clear both fields and type their password yet again if you don't end up just losing the user entirely. This is all avoided by simply toggling visibility of the password to verify its value and if they did manage to type it wrong they can recover with forgot login, but statistically the chance of that happening is little to none since again people get their passwords right the first time basically 99% of the time. Given we're in a world of modern password managers as well people often aren't typing their passwords either.
Suppose you accidentally make a typo in your password. A second password field would detect this, before saving.
They can unmask the password to check it if unsure. Worst case they use forgot login to reset it.
With all that said the verify input field is not going away and by all means continue to use it if you want to. The unmasking feature is also entirely optional, but is default enabled so simply disable it if you do not want it.
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