Well, nobody needs anything 100% of the time besides oxygen. But if you pay a lot of money for a watch because it has certain features backed by services, I would definitely hope that I can actually use them when I want to.
and nobody can guarantee 100% uptime of online software services. Not to give a free pass or excuse downtime, but you shouldn't expect 100% uptime if its not in an SLA you are paying for, which would be quite expensive