But more importantly (for me), because they have such a huge catalog, and a propensity to optimise, they ended up with a supremely hackable furniture - everything fits together with everything else, whenever you want to build something - there are tons of parts available - and you can buy just the parts its kinda like lego.
Also a lot of Ikea stuff is made of honeycomb paper - so it's trivial to put cables and electronics inside. I've hacked multiple tables and sofas by putting charging ports / wireless chargers and other doo-dads inside, vastly decreasing my cable management issues.
And again if anything breaks, its kinda trivial to fix it yourself, as you've probably assembled it and know where each bold and nail go.