In some less enlightend countries perhaps, here in the UK we had access to the from 1951 onwards;The instrument has an accuracy of ±1% of FSD on DC current ranges, ±2% of FSD on DC voltage ranges, ±2.25% of FSD on all AC ranges and ±5% of reading (at centre scale only) on resistance ranges. Its maximum current draw of 50 μA at full-scale deflection (corresponding to 20,000 ohms per volt) is sufficient in most cases to reduce voltage measurement error due to circuit loading by the meter to an acceptable level. Had mine around 25 years, still works well.
How many people remember why there was a mirror strip on the label with scales behind the pointer.
Discrete logic powered by batteries? No, that was never the expected thing, early logic families arevery power hungry, bulky and non portable - mains power was assumed(*). 5 is a nice round number,I suspect its as simple as that.(*) These chips were developed for mainframe computers, for instance.
Also, old valve (tube) heaters ran on 6.3V (why 6.3? ) - it was relatively simple to build 5V supplies with the transformers. (BT,DT)
Another mechanism that produces a similar effect is the avalanche effect as in the avalanche diode. The two types of diode are in fact constructed the same way and both effects are present in diodes of this type. In silicon diodes up to about 5.6 volts, the Zener effect is the predominant effect and shows a marked negative temperature coefficient. Above 5.6 volts, the avalanche effect becomes predominant and exhibits a positive temperature coefficient.In a 5.6 V diode, the two effects occur together, and their temperature coefficients nearly cancel each other out, thus the 5.6 V diode is useful in temperature-critical applications.