Amazing that GOG was so lazy that they didn't check to ensure their DRM removal was complete, before offering it for sale. Hopefully this will motivate them to do a proper fix.
I would not blame GOG for that if even the official 1996 bundle release made the same mistake. The description in the article sounds like it was never officially confirmed knowledge that the game would become unwinnable if cracked incompletely.
How would you check for something you don't know about? They probably tried the game and when they couldn't win they ascribed it to insufficient skill. Even if they searched for information online, they probably (like OP) found discussions where some people complained about the game being unwinnable and got "you just suck!" replies.
Honestly, it was a dumb thing to do by the original developers.
QA should be playing these games to completion. At least one of the events in the game was completely unwinnable.
Devs then and now use poison pills like this to discourage dishonesty, and I don't fault them for it. It's hard to make a living producing digital content that's easily replicated at almost no cost.
I very much doubt that GOG makes enough on such old titles to justify thorough QA.
And I absolutely fault the developera for it, because it's a stupid, counterproductive thing to do - if nobody knows it happens because the game is pirated, it will just get a reputation for being buggy and deter honest buyers just as much as pirates. So why do it? To secretly "get back" at the pirates?