Almost all furniture in my room is Ikea (except the table which is custom) and the 3 year claim is definitely wrong.
We even own our Ikea kitchen for over 12 years now and it still isn't broken at all. The only thing that broke in that time is the oven at the beginning of this year.
Bought my Ikea kitchen when moving into this house 17 years ago. Got a new one this year because of water damage due to a leaking pipe. Most of the stuff was still in good condition though.
It isn't. I have a bunch of ikea furniture because I'm not really settled in where I live, so it's nice and easy and lightweight to take apart and move every 3 years. For one, it absolutely isn't that expensive, and it's pretty good quality. My oldest pieces are two kallax units that were already second hand when I bought them 6 years ago, and they're still in the exact same condition as when I bought them, even through 3 moves. The only thing I'm disappointed about are a couple of wooden folding chairs because the horizontal slats tend to get loose and fall out, but you can just pop them back in in 5 seconds. It's obviously not as good as high quality non-ikea furniture, but if you (have to) move often and don't have much money, it's just a good and practical choice.
Ikea is not the same grade as custom made real wood furniture, that is true. But it is exponentially cheaper and easier to transport. And on top of that, speaking specifically about Ikea vs other similar options, it is roughly the same cost but in my experience higher quality.
If you go buy flat pack consumer-assembled furniture from a big box store like target or Walmart, in my experience you've got at least a 40-50% chance that you are missing a piece, it's damaged, the instructions are shit, etc. Since we started buying stuff at IKEA I have done quite a few builds. Never once have I even had a missing piece. But on top of that the quality control on the machining and fit of parts is head and shoulders better than equivalent options from other big box stores. I never have to force things, they fit as designed, etc.
I'm not here to say Ikea is super high quality furniture compared to real, heirloom quality furniture. But it's laughable to claim that it doesn't occupy a very useful and necessary niche between real furniture and Walmart crap.