Substitution Failure

The internet is a mecca for cooks like me who don't always have exactly what a recipe calls for and don't feel like running to the store. All I have to do is look up "substitutions for blank" and a whole page full of links pops up. I've done this so many times with decent results that I now laugh in the face of any foreign ingredient that doesn't have a place in my cupboard. Well last night substitutions got the last laugh. The internet said I could substitute 1 ounce of baking chocolate plus 1 tbs of sugar for every 1 ounce of bittersweet chocolate that the recipe called for. UNTRUE. After refrigerating the dough overnight it was rock hard this morning. Like, if I had dropped it on the floor it would have potentially cracked my ceramic tile...or broken my foot. The only other time I remember having a substitution that worked this poorly was when I was making humus and needed apple cider vinegar but substituted (suggested by the internet) white wine. It tasted fine, but after snacking heartily it made me a little dizzy...so maybe that wasn't entirely a failure.
So the lesson here? If you don't have anything nice to say, don't say anything at all. Wait...that's not right. The lesson here is Don't believe everything you read on the internet! This lady knows.