It was definitely popular in Europe, you just had to look at the right places. Both CP/M and the multi-user variant MP/M were used in e.g. accountant offices, and the reason is exactly as an earlier comment said - CP/M and MP/M could run on tons of different hardware, so you could start with choosing which hardware worked best for your use case / office, and then just run CP/M or MP/M with the software you needed. Accounting, for example. I remember visiting an office with 8 terminals connected to an MP/M box - I can't recall at all what that hardware was, except that it was probably built in northern Europe somewhere. I went there because they had accidentally deleted all the files on their harddisk, and needed a rescue.. which wasn't difficult to fix.