On a hard-money system, monetary rewards can only be attained by providing value to others who also provide value to others. The extent of your reward for servicing your customers is proportional to the extent of the economic value provided by those customers in aggregate (in terms of how they service their own customers). It's more profitable to service people/companies who are effective at servicing others.
In a soft-money system, there is no guarantee that a specific entity earned their money through value creation; e.g. the money could have been sourced from a loan from a now-bankrupt company which provided no economic value (just spent the money into the economy and went bankrupt soon after)... Or it could come from huge, overpaid government contracts. It could come from corrupt dictators who are laundering government-issued money between each other, etc... With money printing, it's too easy to spend money which you can just create out of thin air. There are too many weak points which can be exploited and which can undermine the entire premise of free market capitalism.
If an industry experiences productivity gains, it does not entail that they would need more workers; the opposite should be true. The entire premise of productivity gains is that you need fewer workers to provide the same amount of value. If the productivity gains within an industry were real, that industry would not need more workers and it would not be pulling workers from other industries and thus driving up the salaries of remaining workers (due to labor shortages in those unproductive industries). Specialized skills are required to deliver productivity gains; it's not like you can hire a petrol station attendant to build your AI with Tensorflow...
What's really going on (a much more powerful force) is that some unproductive industries are subsidized by money printing so they grow regardless of the value they bring to society and they just create bullshit jobs. Workers just move from industries which aren't well subsidized by money printing to industries which are. This movement of workers does drive up increases in salaries in other industries, but it has nothing to do with productivity. If anything, the fact that some industries benefit more from money printing than others may explain why there is such inequality in productivity growth across industries. Money printing creates incentives which, for example, keep tech workers out of certain industries (since they can get paid more to work a bullshit job). Why are so many tech people working for Big Tech (where they are clearly not needed given the recent rounds of mass firings) and so few working on farming, building/construction automation and robotics (for example).