like saying practice for football is useless.
Comparison to a "practice" game vs a "real" game is bs.
A professional (or wannabee pro) athlete who doesn't possess or loses the competitive mindset is destined to fail. "Practice" does not change that. Practice games and real games are the same in this regard. Additionally, injury and all the consequences can occur during practice. Sports practice makes one stronger, faster, better... a necessity for completing a season and advancing a career. A "winning" mindset exists or does not.
Sim Trading and real trading are not the same. No injury is possible with sim. No real-life consequences are possible with sim. No "winning" mindset is needed with sim. Once you know how your platform expects it's input, building up the strength of your mouse finger has no value. Typing faster than your keyboard can process likely has some value, although most value would be in a non-trading usage. Price, as a numeric value doesn't matter either once you know how your platform expects it's instructions... You are attempting to buy or attempting to sell, based on a playbook you have designed. There are order types. In football, a play is determined in the huddle. When the team is positioned on field, the QB can change the play through an audible. Audible or not, whether everyone gets the memo or not, the play, the game, continues.
Bottom line: No injury is possible with sim trading. No real-life consequences are possible with sim trading. No "winning" mindset is needed with sim trading.