Garbage Collection, in my understanding, will keep copying the deleted blocks over and over again. Massive write amplification for deleted data.
What someone should really do is develop a new filesystem for SSDs. The ones we are using are for a long-outdated model where drives write bytes in a specific place with no way to understand what the bytes are or how they are related to bytes in a different place. Put some of the FS logic on the drive, there's lot's of processing power available for it now, and get an SSD that doesn't need TRIM commands. When you delete a file, tell the drive to, and it deletes the file.