Why cant adobe add editable stamps?

Here's a video that shows how to create a dynamic stamp.

https://www.youtube.com/watch?v=DePWr_1lnYg

Maybe it would help if i better explain what im trying to accomplish--maybe i dont need a stamp per se, but i will use that word loosely in my description.  We get dozens of invoices a day, that get processed by each department in their respective folders.  When they open each invoice, we need a "stamp" that they can drop onto the invoice. 

The "stamp" lays out like this:

Building:___________________

Unit_______________________

NR____TR____BD____CAM____

Approved by__________________

Description________________________

I have made the "stamp" already and have inserted text boxes on each line and when i open that PDF of the "stamp" the lines are indeed fillable and works just fine.  Where the problem lies is when this is an actual stamp and i drop it in, it is of course not editable as everyone has said.  How else should i be trying to accomplish what i want? A fillable form seems ideal, but i cannot for the life of me find a way to add it ON top of an existing pdf.

If you want to just drop a fillable form onto an existing PDF page, then use a Page Template. This is a very old feature that was designed to do exactly what you are asking for. 

This issue is not with Adobe, but with the PDF specification.  Stamps, as specified, are annotations that use custom images.  There is no such thing as a dynamic interactive stamp in the PDF spec.  That's somehting that Adobe provided us by accident as a feature in Acrobat. They never intended it to become public.

However, if you wanted to create such an animal you could absolutely do it by creating an Acrobat plug-in that adds your own custom annotation to Acrobat. 3rd party developers have created all kinds of custom annotations. 

Or you could lobby the PDF standards committee to put it in the spec.  But I don't think you'll get very far. I doubt there is much interest in such a thing, since they have to worry about how well such a feature would be adopted. And since almost no viewers support interactive stamps, much less the scripting needed to support it, the chances are poor. 

Or as try 67 suggest, this type of feature can be simulated with a folder level script. I've done it a couple of different ways. 

1.  Recreate the stamp appearance by deleteing the APCosObj property. 

2.  flatten the stamp into the PDF page and add fields over it. So the stamp acts as a kind of stampable mini form. 

It is possible to achieve it, actually, using a custom-made script, but it requires some additional steps by the user. If this is something you're interested in purchasing feel free to contact me privately to discuss it further.

But it's not likely stamps will ever work that way, as their functionality is not as interactive elements, but as a static comment on the page.