The alternative is starting every trial over every time someone crosses the line, and even if you heavily sanctioned the lawyer every time, the amount of extra stress on the system itself and the actual participants would be massive and detrimental.

Forcing a mistrial is already a(n extremely unethical) tactic that’s entirely possible in cases where victim testimony is particularly painful. Even if every judge sanctions every lawyer who enables it and they get disbarred at a high rate, it’s still something enough money would enable to happen.