I just tested a S9 I have running on solo right now with a backup pool of Kano.  In console I switched to kano and timed the difficulty adjust.  Diff stayed at 1042 for exactly 60 seconds and then switched to 8.38 K.  Before I had done this test it was running at 10.8K on solo and had been for days.  When I switched back to solo diff quickly dropped down from 10.8K to 4K after only a few minutes of no hashrate.  I understand about the smaller miners but as you said they will probably never make money mining, so why cater to these in-efficient miners?

I have seen entire 300 TH workers disconnect on NH ramp up due to the difficulty not adjusting quick enough.  Large hashrate rentals on MRR are the same way.

X