My elk rifle is a 700 ADL, synthetic stocked '06 made in the mid-90's. It has, as has been discussed, the "safety on" bolt operation feature. All my center-fire bolt guns, which haven't been very many through the years, all locked down with the safety on. My vintage 80's Ruger M77 (tang safety) is that way, and my first deer rifle, back in the 60's, was a 7.7 Arisaka. I haven't had that rifle for a very long time, but I'm quite certain that the bolt was locked down when that big thumb safety was "on." I just acquired a really nice vintage M700 ADL in '06 made in 1968, which has the bolt lock down feature with the safety "on." Personally, I'm glad it's that way.
When I got the syn-stocked late model 700, I didn't care for that bolt operation feature while the safety was "on" at all. The first thing I noticed was that if the bolt was accidently raised/opened close to half-way, safety "off," the rifle would fire (I tried this as a test with the rifle empty), and the bolt would slam down to the closed position, dropping the firing pin. I could also see, as has been mentioned, that while hunting, that bolt could be opened on some brush while slung during a hunt, and that would be bad.
FWIW, I've never had any problems with that newer 700 whatsoever, and it's just become an unconscious, built-in thing for me to when I bring that rifle from slung mode to a "ready for a shot" position, I always run the palm of my hand over the bolt to make sure it's completely down, thumb ready on the safety; it's just an automatic thing anymore, and again, no problems.