Sorry to cloud the issue, pun intended, but the advice my company has from Boeing is that ice crystals do NOT always paint on the weather radar. So it's a tad unfair to lay the blame on crews who one hopes would have actively altered the range and tilt on the weather radar system.
I've seen some huge CBs that didn't paint at all and was thankful that being VMC we could see and avoid. At night I'm convinced I encountered the tops of such cells judging from the St Elmo's fire and turbulence. In one instance we were most definitely scanning at different ranges and tilt angles.
The other thing that my company has instigated is a flame out mitigation procedure on advice from Boeing. Basically it's Nacelle Anti Ice on in moisture during the descent and Wing AI as well below F220. If it proves one point is that even the manufacturers constantly review and revise their procedure in the light of experience.