I feel for the team having to deal with these problems at github today. Its also beyond me how those in charge for years wouldn't have seen this coming.

Github was bought by Microsoft, whether they wanted to acknowledge that internally or not. Microsoft went deep on LLMs, and specifically on LLMs for coding use cases. They must have recognized that LLM generated code and PRs would effectively DDoS GitHub.

I can only assume they simply didn't care, likely driven by greed.