meaning in context - What is "as English verbs go"?

I found the clause "as English verbs go" in one of the answers on ELL:

In The Cambridge Grammar of the English Language (p.113-4), this is called "motional be", and it's very unusual as English verbs go. In this meaning, be appears only in perfect constructions [...]

It was later edited to say:

In The Cambridge Grammar of the English Language (p.113-4), this is called "motional be", and it has a requirement that's very unusual. In this meaning, be appears only in perfect constructions [...]

I tried hard to understand the meaning of the "as English verbs go" clause but failed. Will anyone clear the meaning of this?

Answer

This is a set phrase. Here's how Macmillan Dictionary defines it:

as someone/something goes
when you consider what other people or things of the same type are like

'As history textbooks go, this one is pretty good.'

I was saying the verb be is very unusual, considering what other English verbs are like.

This use of be appears only in perfect constructions. Very few verbs have that property, so be is unusual "as English verbs go".

Actually, be has lots of different properties that are unusual, but I wanted to focus on this particular use being unusual. That's why I decided to edit my post.