If you look at it, for any large or small scale system, the probability of failure relative to scale becomes lower in larger systems.
For small scale systems, they individually seem more reliable, but if you put 500 customers on 500 systems compared to 1 system, the former will have a higher overall failure rate.
The probability of experiencing downtime as an individual with a large system is not much different than a small system. But if a big system fails, more people notice, and it feels bigger.
With small systems, the frustration is spread out over a large time period, and so it feels like it never happens.
The distributed systems world has figured this out ages ago and this is why there is fault isolation, so that failures are contained, and become another ignored blip.