I agree that there are many fields of business where this indeed is possible. In recent years I noticed that online stores and services will simply address you in an informal way with your first name. Since “Dear” still won’t work, they will address you with “Hi” or “Hello” which is truly gender independent even in German. I’m not sure I’m a fan of that, though.
And usually they won’t do this consistently anyway. As soon as it’s not the newsletter or another impersonal message anymore but a real person getting in touch, we’re back to the formal, more polite way of addressing each other.
And once we reach the point of one-to-one communication, you wish to be able to address that person correctly. Furthermore, why risk typos when the information is stored in your database?
That’s why, in my opinion, a person should be able to choose themselves how they wish to be addressed.
You mentioned non-binary people. The website www.nonbinary.ch recommends not to differentiate genders but to differentiate salutations. They recommend a selection as follows:
Say Max Muster is registering. If he chooses the Anrede “Herr”, our full salutation will be “Sehr geehrter Herr Muster”. If he chooses the Anrede “Neutral”, our full salutation will be “Sehr geehrt* Max Muster”, or “Sehr geehrte_r Max Muster”, both examples seem to be accepted as neutral. I’d be perfectly happy with such a solution. But that would require the ability to use the field “Anrede” in a condition.
One could argue, why not choose the neutral salutation for everyone, thereby getting rid of the issue in the first place? It’s a valid argument and things would be simpler. But I know that many if not most people will still prefer the personal touch of a salutation that takes into account their name, gender (or Anrede), and potentially even their title if they have one (such as Dr.).