Actually, Delta's manuals allow all three techniques for the 767.
Landing in a crab is basically discouraged on dry runways, but is always permissible up to the landing crosswind guideline of 40 kts wet or dry. "On very slippery runways, landing the airplane using crab only reduces drift toward the downwind side at touchdown, permits rapid operation of spoilers and autobrakes because all main gears touchdown simultaneously, and may reduce pilot workload since the aircraft does not have to be de-crabbed before touchdown." Sideslip only (cross-control) landings are not recommended above 28 (757) or 26 kts (767) crosswind component due to nacelle clearance.
In the E-6 (707), which is
quaileman's military background as well as mine, only the first two were permitted, due to very small clearances between the inboard nacelles and the ground.
In the 747, I continued to prefer the de-crab technique, because it was what I'm used to, although cross-control landings were permitted. Same in the 767. (I do put a tiny amount of upwind aileron accompanied by downwind rudder, which is a trick an E-6 IP taught me a long time ago that works surprisingly well to dampen oscillations due to gusts and smooths out the de-crab maneuver during the flare.) However, according to the charts in the FCTM, it's impossible to strike a pod at a positive pitch angle in the 767, so this is pure personal preference. Depending on the pitch angle, you could drag a tip beginning at about 12 degrees of bank. Short of that, the tailskid hits first.
In all three aircraft, the main mounts are engineered to land in a crab up to the maximum crosswind component for landing. I'm sure this does increase tire wear, however, and doesn't make much sense under normal circumstances on a non-contaminated runway. However, the de-crab in the flare maneuver aligns the aircraft with the runway centerline just prior to touchdown and does not place side-loads on the gear and/or tires. The hard part is judging the timing, but it's not like if you land in a slight crab the main mounts are going to snap off or the tires are going to blow. (Just like you don't actually have to flare, you don't really have to de-crab either, but everyone tends to like it better when you do both, conditions permitting!)
This video shows Boeing's test pilots using de-crab and touchdown in crab techniques during validation testing of the 777.
So it definitely varies from aircraft to aircraft and even pilot to pilot in some cases. I'm am surprised at how many people here are so quick to decree that another pilot's crosswind technique is dead wrong when they've never actually flown the aircraft in question, and have maybe only flown one large or heavy aircraft, or even none at all!