In all my years of offroading, I've only ever lost a bead once. I had to drive off the trail to avoid a mountain biker and I hit a rock that pulled the tire off the bead while cutting the sidewall bad enough it required tire replacement. Unless you're running under 25 psi at high speed I can't see a need for beadlocks, under 25 psi you'd probably overheat the sidewall and damage the tire anyway. Using the same 315/70R17 tires on my 5500# Bronco I found that 18 psi was the sweet spot for crawling and general trail use. For high speed wash or dirt I was good around 25 psi.
up to 50-60 MPH in rutted sugar sand at 18-20psi, and slower speeds as low as 12 PSI
sidewall damage? Yes, thats why I am mounting my old ko2s on the BL set and run two spares
Are they absolutely necessary for what I do, after 20 years of beach driving, no, but they look damn good and it gives me some more flexibility for really lowering tire pressure if I want or running harder with less worry
These are my second set, not my daily driver set.