"...Is it the bolts don't lock up as securely as a bolt gun?"
I'm not an expert, so bear with me -
John Browning was one of the first to cook up a lever action design that would handle spitzer bullets. I believe the Winchester 1895 was eventually chambered for the .30-06. I've read that the early ones didn't like this as the locking mechanism is at the rear of the bolt. Load manuals sometimes recommend staying away from maximum loads for historical 1895's. Modern reproductions (Browning mfgr, Mikoru) are supposedly OK, due to stronger steels.
So, the Browning company (not John Browning) eventually solved this with a lever action that uses a rotating bolt that locks up like a bolt-action. Their modern BLR is offered in all sorts of modern, high power chamberings. The bolt locks into the barrel, not the receiver, so they can even offer a lightweight model with an aluminum receiver (!)
However, most lever-actions, such as Winchester 94's and Marlins, lock up at the rear, I believe. The actions just aren't strong enough for .308's and their kind.
Hornady is pulling clever sleight of hand with carefully formulated powders that offer extended range by burning slower, without exceeding SAAMI pressures for Winchester and Marlin lever action designs. Combined with a higher BC (ballistic coefficient) bullet with a soft tip for tubular magazine safety, this does revolutionize lever action capabilities.
It's not chambering a .308, however, for good reason.