Best thing to do with the tuner on an engine that is still MDS equipped, is to bump up the idle to 700 +- 50 RPM to get some more oil splash going on in there. Yes, I did that with my tuner.
Did I turn off the MDS with the tuner in my truck? Absolutely not. Do I use the steering wheel buttons at times? Yes I do around town or when driving it with "spirit", usually when MDS won't be on to begin with and RPMs are up. I use tow / haul switch when towing my boat, too (which also turns off the MDS). The wheel buttons also change the shifting pattern on downshifts (if you just leave the top set gear to *8*) to be more aggressive and lock converter to use engine braking. Well, on mine it does, anyway (I used AlfaOBD to enable engine braking BTW).
Personally, I believe there are 3 main causes of these failures. Just one or any combo kills the engine:
1. Oiling of MDS lifters when MDS is off is sub par. Oil squirters on all the lifters / cam lobes would have prevented a lot of failures here. On an MDS deleted engine, the Johnson lifters address this by adding a small oil passage to the lifter to feed oil to roller (and cam)
2. A run of crappy/poorly designed lifter rollers with small / weak roller bearings (the new design in 2017 / Hellcat was a huge improvement)
3. A run of soft cams.
This is just all my humble opinion.
