Why do some websites/applications require that passwords must begin with a letter?

Question

Some number of websites/applications require that a password must begin with a letter, I find this plain stupid. It's pretty annoying... and the password entropy (security) is greatly reduced. So my question is... Is there a reason why some developers would choose this?

The only reasons I could think of are:

• They are sheep (Seen it required somewhere else and just copied the trend)
• Some just implement it because that's the little regex they know
• Just to create a false sense of security for their clients

(Asking because I'm developing an app to manage user passwords and thinking to alert the users that if the website asks for that, they should not trust their security)

Answer 1

Regarding security there is no reason such a password requirement makes sense, you already gave the answer yourself. I do not think that giving out a warning is necessary though, because the implementation is not necessarily an unsecure one.

In my opinion the only reasonable restriction for passwords is a minimum length. Other requirements can interfere with good password schemes and can actually reduce the strength of passwords, because users will switch to weaker passwords like "Password2014".