More helicopters in the country, more hours being flown, and more prangs of memorable note. Helifix, Pacific, Hevilift, Islands, HNG have all had prangs in the past year or 2. That just leaves one long term charter operator to be prang free, ever. But who knows the accident rate is anyone's guess as it is PNG, and there is no such thing as an accident investigation in PNG, and probably no official prang statistics either. I've certainly never seen anything official.
If you look at the pilots who are involved with the prangs, there's not much to conclude there. The double prang pilot is very experienced PNG, the HL and HNG fatals were both experienced pilots but not experienced in PNG (both on first tour), the Pacific prang was an experiened PNG pilot, and the Helifix prang was an inexperienced national pilot. So anyone can have a prang whether experienced in PNG or not.