That's probably true, although I don't for a minute think that the Sebo is perfect. Of course it has it flaws! The topple over when using the short hose, the weak cable connection on the handle, the auto height adjustment can be temperamental (not a problem I've had on either of ours, but others have reported it here). But whilst it's not perfect, I've found it ticks other boxes that work for me, tipping the scales in its favour. There's pro's and con's to every single vacuum on sale.
I honestly believe that the Kirby is unrivalled for carpet cleaning, but severely lacking in terms of weight, easy of use, noise and price. I also noticed that the Sentria 2 tools felt very cheap and basic. Not what I'd expect from something I invested over £1000 in.
Now, the D80 I got from Paul is a fab vacuum. It really does incorporate all the good things about a Kirby into a smaller, lighter machine. But again, you're stuck with faffy tools. Having to cart around a huge chunk of metal AND a tool caddy just to vacuum up is not something I ever fancy doing.
It's 2014. The "housewife" role doesn't exist anymore and people don't have the same amount of time they used to for housework. The market now calls for cleaners that are good but quick. You can argue the toss all you want, but there's no denying that vacuuming a house with a Kirby takes a lot longer than most, if not all, other uprights. People these days want their house cleaned quickly so they can get on with other things - better things! Kirby need to get with it.