XML is ok, the problem IMO is that the way some people use(d) it is utterly unhinged.

So a return value that could have easily been two lined of text is now a nested demon of XML. The complexity isn't what that application does, the complexity is in how it returns the values.

Another good one is to use XML when something else would have made things simpler, e.g. for a config file where you could easily have used a .ini or a .toml file.

Or you have an application that tries to so generic that the definition for a simple use case is a whopping 5MB XML file. Cool. When I feel writing a config for your application is harder than programming the whole thing yourself you have really made it. /s