Macs have unified RAM and a special MLX framework for AI purposes tailored to their M chips, which makes it possible running full sized ChatGPT/Gemini/Deepseek level LLMs locally without serious limitations. You can also join 4 macs using lightning port and make a cluster for LLM/image/video generator model. It’s a real bang for buck stuff compared to other platforms for personal use. So they disappeared because they are mostly sold out, even after price increase.