The reason for the insane popularity is because it's pretty good AND free. It's a no-brainer to switch to this for anything usage-based that isn't frontier coding while the free limits are available. It's probably running a model ~100B parameters under the hood, which won't be so heavily subsidized for long.

EDIT: our tool usage benchmark is still running, but so far, its performance with tools is dramatically better than its one shot performance. I'm treating Qwen 3.6 Plus as a near-SOTA model now.