Just speaking purely about wood joinery, there's a difference between how tight a joint is and how strong it is. Of course, you can also have both, with varying degrees of each.
You really can't glue on a neck that's designed to be bolted on, no matter what glue you use. You would end up with what's known as a "lap joint", which by itself usually isn't the strongest of joints, and it would have too small an area for the amount of force it's expected to withstand. Long story short, the neck would come off with very little effort, kinda like a Gibson headstock.
A neck that's going to be glued needs a lot more surface area for the joint interface, and possibly some interlocking cuts to prevent movement. So, you usually see very large dovetail or mortise and tenon joints. Nothing holds the neck on but glue, but there's lots of it. Not very tight, but generally pretty strong.
Bolting the neck on changes the game. Now, rather than a glue joint, you're relying on the strength of the fasteners and the shear strength of the wood, both of which are generally high with the woods typically chosen for bodies/necks. Because you're applying clamping force with the fasteners, you also end up with a much tighter joint as well.
So, properly designed glue joints will give you strength, but a less tight connection. Bolted joints give you strength and rigidity. Which is better? I don't know. Do tomatoes taste better than apples? Does a Robin sing better than a Bluejay? Which of your daughters is prettier?