Everything mechanical needs some maintenance. And can breake too. Without exception.
But - from experience - such stories are hugely exagerated.
I have one 500 C/M body, in regular use, that hasn't been serviced since i got it new 30 years ago, i.e. never. Never a problem either. That is rather silly, but not surprising either.
Other cameras i have have been serviced since i got them. Not because there was something wrong with them.
These thingies really are "paragons of reliability", as Geo put it.
The backs do need some regular maintenance: the foam pad, part of the light seal will go bad, and will need changing every 2-3 years (you can do that yourself. Not difficult, and takes a few minutes).
And a nylon stop may get dented and then will need changing once every 20 years or so (very much depending on use; you may never have a problem at all).
If there are problems, most are fixed by cleaning and retightening of screws. Just about all problems with backs are solved by that. Cameras with problems too hardly ever need anything else but readjusting the mechanism.
The only problems i have had since i began using Hasselblad were with lenses: the fast shutterless lenses have a rather finicky diaphragm mechanism, and on two of mine (110 and 150 mm) failed and needed parts.
And i once got a used automatic bellows unit, that came with problems. Was fixed.
There are a few sources for problems with Hasselblads.
The first is non-use. Leave a camera or lens unused for a longer time (think years) and the lubricants will go stiff.
The second is over-use. Things do wear. Springs may need replacing once every decade or two. Screws will work loose a bit. Things will slip. That sort of stuff.
The third is abuse. Don't need to explain that, i think.
The fourth is people seling their cameras and lenses they have 'exposed' to the first three. Especially nowadays, with prices low, repair costs still high, it's tempting to sell a camera with a problem to an unsuspecting buyer and get a cheap replacement rather than spring for the repair costs.
The fifth is user error. And that is responsible for 99.9% of all reported problems not due to the first four. If you know what you are doing (and it's not hard: on the 'simplicity level' of being smart enough not to hold a lighter to you shoe laces if you do not want them to go up in flames), you never have a problem.
The sixth is perception and envy, and 'partisanism'. Psychology.
Many reports of problems are bogus, put into the world by people who - for instance - would have wanted a Hasselblad but can't afford one, and then start kicking. Out of spite. And to set their own minds at piece with the fact that they have to do without, trying to convince themselves that it would have been a bad thing anyway, that thing they would have wanted but have to do without.
And you know how it goes: drop the word Nikon in a Canon forum, or vice versa, and all hell breaks loose.
(And see how Rolleiflexes are "totally reliable" just one post above?

)
And finally, things will break. Hardly ever happens. But it can, and will.