Steam technology was simpler. Simple enough that it was possible to implement by (the most advanced) preindustrial society. It may be that industrial-grade applications for electricity, such as transport, require the much greater degree of wealth and sophistication that steam made possible.
I disagree that steam power is simpler. Watt needed precision lathing from Wilkinson, the famed man of iron, before he could produce a steam engine worth anything more than a water pump. No precision tooling, no steam engines (Newcomen gets an honorable mention).
Meanwhile, a dynamo is incredibly simple once you know what you’re doing. Or, to put it this way: if you (actually you in AD 2018, not a hypothetical you in the 18th century) had to build one of the two from scratch, what would be easier?