Others have covered the most obvious flaw: it was 100% ineffective, causing chaos in government without any meaningful spending decrease.

But here's the real reason, and it comes together with the other real reason: DOGE was never intended to be about "government efficiency". It was intended to give Elon Musk access to all the information he could get his grubby little hands on for private enrichment and to shut down the very government departments that were in a position to regulate his companies.