It seems very plausible to me that there was plenty of crappy (probably homemade) furniture that wasn't any better than Ikea historically. Heirloom quality furniture takes real skill, time and materials to make. I can't imagine that the average pre-Ikea family would have been able to afford for all of their furniture to be of that quality. Not being any kind of historian, I have no idea how they filled that gap.
The problem is that people by and large don't want solid and reliable. They want a wardrobe with a full-size mirror and soft close drawers, not grandma's hand-me-down mahogany wardrobe that's built like a brick shihouse.
This thread is also full of people complaining about IKEA products not holding up to moves, but I bet most of them would change their tune if they had to move a house full of solid wood furniture.
That stuff is heavy. You can buy an old wardrobe that will barely dent when hit with a sledgehammer, but the labor cost of moving it is so high that it can be cheaper nowadays to scrap it and buy a new one from IKEA.
Speak for yourself. I just finished a long distance move, and I absolutely took all of my Ikea furniture apart.
I'm on about year 3 of my current set of Ikea furniture, and so far it's all holding up fine. I pretty much just followed the directions, and used a power drill (with appropriate torque settings) for pretty much everything.