I think that has face validity. However I don't think that those who pay wages allocate a certain amount, pay benefits and then pay the rest as wages. More likely they pay a little as possible (both wages and benefits) to fill the jobs. (Econ 101...)
I think a more likely factor is that automation has reduced the number of jobs relative to the size of the labor pool. In that situation more workers chasing fewer jobs will tend to drive wages down. (Again, elementary economics.)
Another factor may be that large employers that dominate a labor market can exert downward pressure on wages that workers are not able to resist if there are not other jobs available. (Not IMO elementary economics.)
I think a more likely factor is that automation has reduced the number of jobs relative to the size of the labor pool. In that situation more workers chasing fewer jobs will tend to drive wages down. (Again, elementary economics.)
Another factor may be that large employers that dominate a labor market can exert downward pressure on wages that workers are not able to resist if there are not other jobs available. (Not IMO elementary economics.)