Because of findings like this

https://www.anthropic.com/research/small-samples-poison

(A small number of samples can poison LLMs of any size) to save clicks to read the headline

The way I think of it is, coding agents are power tools. They can be incredibly useful, but can also wreak a lot of havoc. Anthropic (et al) is marketing them to beginners and inevitably someone is going to lose their fingers.