Is baking by weight really more accurate? It's gospel among serious bakers that measuring by weight is far more accurate than measuring by volume.  However, I'm not sure that measuring by weight helps at all when you have varying humidity levels. It seems to me that, if the recipe author has much higher or lower level of humidity in their kitchen than you do, measuring by weight would tend to make differences in water balance even worse.

For example, I recently made the same pizza dough recipe in my apartment (65F, 80% humidity) and at my in-laws (75F, 35% humidity).  Getting the same texture of dough was a difference of 2/3 of a cup of water, or around 6oz of weight.  This water already was clearly in the flour in my apartment, adding to its weight but adding somewhat less to its volume.  This means that if a recipe was written by someone in Tuscon and I made it in San Francisco, I'd get a sticky mess of a dough without enough flour.

Unfortunately, I'm not in a position to make repeated experiments in measurement at different humidity levels to see if weight or volume is more accurate when the hydrometer is going up and down.  Is anyone?
Is it more accurate?  ABSOLUTELY

Does it mean that you can still follow a recipe by weight exactly and expect perfect results everytime?  No

You're right in that humidity will vary the weight, but if you're consistently working in the same area with a small change in humidity - its not something to worry about.  You'll adjust your recipe once and then generally stay in the same range.  Going by volume, you're always going to be all over the board.  Sometimes you'll pack light, sometimes tight.  Going by weight, you're going to be pretty close as long as none of the variables have changed drastically.

The problem you run into is when you change locations or the humidity changes drastically.    In the long run, you'll need to know what your expected dough should look and feel like.  After you've baked a loaf 100 times, you'll poke it and know if its too dry.

In addition to the feel of the dough, I have a hygrometer in my kitchen.  Keeping an eye on it lets me know if I should expect to need to add more or less water to my dough.  I bake A LOT, so I keep an eye on this to make life easier.