switched from analogue to digital computers 70 years ago
We were still seeing mainframe computers with analogue/digital architecture in the 1960s. Indeed, they were popular enough to have two flavours depending on which technology "drove" the beast.
I'm 63 and I remember them from when I was about 11. So the "70 years ago" figure isn't anywhere near right.
I believe it also mis-states, albeit contextually, what an analogue computer is and does. Analogue computers, which were still available from Heathkit and other suppliers in the 1970s, are spectacular for modelling continuous solutions to calculus problems. They don't do arithmetic, at least not well, and the one's I've seen and used are not programmed using a high-level computer language, but with a series of patch cables linking the various integrator circuits - rather like the old DX7 used patches (albeit digitally executed) cross connected the six operators that made the noises. The Analog Computer at Coventry Tech was used to model n-body motion issues and on open days was used to display a snooker game.
The analogue computer was thought to be important when digital computers had low clock rates and no memory to speak of. Now the discontinuous nature of the calculation can be hand-waved as too small to matter, and he results can be smoothed using mathematics anyway now there is memory available for the functions involved.
But years ago that wasn't the case.
I'm not sure why you feel the issue of bits flipping can't be mitigated the way it is for "traditional" storage techniques (which can also fail in this way) by use of a checksum. I believe SSD storage has other on-chip mitigation stuff too that deals silently with cell failures, though I'm not clear on the details.