Because it isn't ineffective. If you are following a celebrity and they have a blue tick, you know that they are that celebrity. Why should twitter care about Facebook? They need their own policy.
The very quote i was responding to said the person in question was impersonated on many platforms, so hence my ineffective. Separate from the fact that the fake blue tick trick by using an background is an thing too, it has been for years.
And just in today is that Twitter now bans accounts that impersonate unless it clearly says ''parody'' so without the need for a bleu tick even without new rules just enforcing the old ones.(it was in Twitters terms for years.) In addition with ''blue tick for all'' you can't impersonate and any username change will mean you temporarily lose your blue tick.
The most effective way would be an site that connects to you social media and then checks certain what you think is a celerity against a list of known accounts.
Most of these scammers however always claim said celerity is lockout of his original account, is ''underground or something like that, there is no way to protect people against that with blue ticks, or any other checks.