" No reason to impute other mechanisms or make things unnecessarily complicated."
Yes there is, because the reason you cited is not the most important cause structural cause of declining wages.
The issue is real wages - i.e. accommodating for inflation.
When we say 'nominal' we mean 'dollar value'.
When we say 'real' - it's an economic term for 'dollars in some present value'.
Issues are far more likely to be causes:
+ Masses of jobs gone overseas. 'High tech' is irrelevant. Here in Montreal, Bombardier employs 66 000 (!) people in jobs - consistent, good paying jobs. That's more than all the startups put together, and those jobs are mostly for the long-haul. So when things like 'Bombardier' shut down, it's a big deal.
+ The other issue is the fact that we may not be measuring inflation correctly. If 'real wages' are down - then why do University students have laptops, cell-phones, can travel, are sometimes even fashionable? I'm not that old and we had nothing. Even 'fast fashion' has changed the nature of clothing as we know it - only 20 years ago ... there was 'the Gap' and everything else was expensive, relatively speaking. Everything is like that: smartphones didn't are exist, and are enormously better now - online services, access to information. The # of people getting access to higher education. Even the quality of cars. Driven an 1980's car lately? The cheapest, crappiest new Honda is like riding in clouds compared to the best Mercedes from 1985.
Even the groceries. My good man - so much choice, so many brands, so much selection. It's amazing compared to 30 years ago.
Inflation is measured against a basket of goods - but those goos also increase in value, i.e. a tomato in 1985 may not be actually the same thing as a tomato in 2017 - if it's riper, nicer, healthier (not saying they are, but could be) - well, that's 'real' improvement, so it's not the same thing.
Very difficult to measure.
Those two things alone: offshoring/outsourcing of jobs - plus - our inability to measure quality of life increases ... would amount to enough that it's a major problem.
Lastly - I would add a financial effect - which is 'low interest rates' - this drives up the value of homes, and expands the disparity between those renting, those in 'starters' those in 'nice homes' and those in 'mansions'. It just exasperates the 'wealth effect' in dollar terms.
Anyhow - those are 'big drivers'.
A 2% inflation target is a really good thing, and it's not just about deflating wages. Nominal wages have kept up with the 2%.