Before XML became a standard and given all its shortcomings, what made XML so popular?

Question

Yes XML is human readable but so is comma delimited text and properties files.

XML is bloated, hard to parse, hard to modify in code, plus a ton of other problems that I

Answer 1

Something I haven't seen mentioned yet is that not only is XML structured, but the way that attributes and elements interact creates a somewhat unusual structure that is still easily understandable by humans.

If you compare an XML tree with its nearest structural neighbor, the directed acyclic graph, you might note that the typical DAG carries only an ID and a value at each node. XML carries this as well (gi/tag corresponding with ID, and the text of the node corresponding with the value), but each node then can also carry and arbitrary amount of additional metadata: the elements. This is very much like having an extra dimension — if you consider the DAG as spreading out flat in two dimensions with each branch, the XML document spreads out in three dimensions, flat, and then downwards to a subtree containing just the attributes.

This is an optional bend to the structure. Walk a list of attributes like any list of child elements, and you're back to a two-dimensional tree. Ignore them completely, and you have a simplified node/value tree which may more purely represent the overall "shape" of contained data. But the extra dimension is there if you need the metadata.

With decent indentation, this is something that a human being can pick up just by eyeballing the raw data, making XML a miniature visualization tool for a potentially complex structure — and having a visualization tool built into the data exchange of your application means that the programmers involved are more likely to build a structure that represents the way the data is likely to be used.