Of course for more than trivial built-in behaviours you'll be writing code, but for a UI prototype, especially if it's just CRUD forms etc., you can get it built in a few minutes with no code. Drop a database connection component and set the connection properties, and you'll get live data and properly typed and bound controls on the form too.
Compilation takes fractions of a second, so that's not an impediment to design iteration - but you don't need to compile or run to see what it looks like since it's effectively a WYSIWYG form designer.
Problem with Delphi-style RAD tools is that there is huge step in complexity between things that can be done in the designer and these that can not. And this invites particular style of "programming" that consists of searching the internet for existing components and connecting these components together with horrible hacks. It is perfectly possible to write well-structured application in Delphi, but most are not.
[Edit: hit reply too soon] Tk model of UI programming does not promote this that much, because causing stuff to happen by writing code is the default way. Also Tk-style approach of writing GUI definitions in code and letting the toolkit to deal with details like positioning (in fact, using HTML for UI is mostly similar) is more productive.
I don't really want to get into a long-winded discussion, but (a) the GUI definition in Delphi is also code (specifically: there's a declarative syntax for constructing a tree of components with property values); and (b) positioning is handled by the VCL. Typically you specify things like alignments and borders in the designer, and the VCL takes care of keeping things positioned.
I really wish HTML was as easy to design with as the VCL designer. Trying to e.g. create vertically centered children is far, far easier in the VCL than in HTML + CSS.
Can you clarify "coding it all together" part. I have no idea what you meant.