It's a step back in a way. Code as XML had DTD with on the fly validation and autocomplete. JSON and YAML are still playing catch up in this area.

I have lots of biases against XML. For me it is nearly personified as Steve Balmer. However, it is rather funny to see people who hate XML yet love html (or even more absurd XAML). The autocomplete feature makes XML somehow not completely horrible as you can easily define a schema and get a kind of mini language with zero effort. Eventually the mind removes the tags and you are just left with the content. However, I see text formats that describe tree structures are all fundamentally the same. It is impossible for json, yaml to be waaaay better than XML as it is the exact same thing.

It's in a way more terrible as it usually is templating language + YAML

So you need to navigate pitfalls of YAML (or bear ugliness of JSON) all while learning a templating language.

All because someone decided "Users will not want to learn Python for DSL, let's give them YAML"...

Every single tool that went that route has that problem and every single one would be better served just picking <language> (Lua is nice and embeddable, just saying) and using it as DSL.