Well, yes and no. Most of the acoustic instruments that have survived over the centuries have had multiple cracks repaired. This applies not just to guitars, but to many different wooden instruments that have cracked and dried, like woodwinds, pianos, etc. If you read up on very old instruments, you'll see that many spruce tops were repaired with strips of cloth or paper glued under a crack to effect a repair. To a slightly lesser degree, these kinds of repairs were also done to the backs and sides of very old instruments.
Also, it wasn't until the mid 20th Century that home builders got seriously into forced air heat. Forced air heat dries out instruments more than the radiator heat that came into use at the end of the 19th Century. Before that, there's a reason people wore gloves indoors, frock coats, etc. So dryness is a worse issue now than it was even 75 years ago.
Every single acoustic guitar maker, without exception, recommends keeping a guitar in its case when not in use, and using some kind of humidification in cold winter weather. Taylor and PRS have made videos on the subject, and Taylor puts a reminder into its newsletter every fall. This is the PRS video:
https://www.taylorguitars.com/sites/default/files/10_UsingaGuitarHumidifier.pdf
https://www.martinguitar.com/images/stories/carefeeding.pdf
http://bourgeoisguitars.net/support/guitar-care/
http://www.larrivee.com/pdfs/Larrivee Care Maintenance.pdf
http://www.gibson.com/News-Lifestyl...011/The-Care-and-Feeding-of-Your-Guitars.aspx
http://www.burgessviolins.com/humidity.html
Here's a quote from Premier Guitar on humidity for electric guitars,
http://www.premierguitar.com/articles/Fighting_the_Humidity_Battle:
"
All guitars should be humidified, even electric solidbodies. Newer guitars generally need more moisture because the wood is kiln-dried, as opposed to a vintage guitar made from air-dried wood. The difference between kiln and air-dried wood is dramatic. Kiln-dried wood uses heat to dry the wood to accelerate the aging process. However, these guitars require more moisture to prevent warping and cracking. Air-dried wood is more stable, especially in vintage guitars, because the wood was generally aged over a decade before being made into a guitar. As a result, the cracked wood was removed from the pile and used for something else. Guitars made from air-dried wood still need humidity to sound best, but they retain moisture better than their modern counterparts."
Of course, I have zero problem with anyone deciding that they don't want to go to the trouble, after all, it's their guitar, not mine. However, it's difficult to argue with the fact that wooden instruments have humidity issues that ideally should be addressed.
