"On the current job market, it seems that some companies do not accept turboprop pilots for their Non-Type-Rated positions."
and
"on current market we have far too much applicants for any job, which gives birth to all kind of strange and non-rational pre-selection criteria - it's just to keep the number of resumees to look at down"
The last quote has the answer: lazy recruiting!
Wait for the shortage that's not too far off (look at how so many are advertising for the first time for ages) and turbo-prop pilots will become popular again.