If you can do 70 reps with an excellent form (every single of them!), it should not be significantly more dangerous than 7x10 or 10x7. So the question can be simplified to: is volume of 70 (perfect) reps dangerous?
It depends on a lot of things. If I imagine a human sample consisting of me and my gym friends doing this volume of training, I would expect the following:
- pushups/pullups once per week - most of the sample with no problems
- pushups/pullups every day - most of the guys would have shoulder problems in weeks or months
- swings/snatches with kettlebell - most of the guys would handle it safely a few times a week, maybe every day
Why? It depends on various circumstances:
- usage of performance-enhancing drugs (PEDs)
- exercise selection
- previous history of injuries
Some kind of sum of these elements might be called work capacity.
To conclude: In some cases, the volume 70 can be ok (even low) and in some cases, it can be considered as a proper hazard.
Note: It is really important to stress out, that the biggest danger of long sets is to keep the technique perfect all the time. If you cannot do it perfectly, it is dangerous no matter how many reps you do.