I understand restricting certain behaviors if they are based upon technical limitations, but I don't subscribe to this idea of hard limiting the options of GM mode based upon Larian's own philosophy of best practices. I am completely fine with Larian having provided starter assets that nudge the players into adopting their play-style. No doubt it was settled upon after trial and error so we should begin with an open and teachable mind towards their counsel. I respect it wholeheartedly.
Still, I think imposing this limitation runs contrary to the spirit of the DOS series as a whole and especially a game master mode. The beauty of an open game master mode is that there are moments that call for special treatment and you have more tools and flexibility to make them happen. If the technology permits a game master to do it, then the tools should err on permitting it. I wouldn't impose such a gentle risk/reward curve on GMs, some of their best moments may be found in taking some risks.
