There's really not much to be concerned with spacers on solid axle vehicles that are 2" or less. Anything larger you should get a full spring replacement. The most important pieces when leveling are track bar and shock length. Most of us will not use the full potential of the spring compressed or extended lengths to experience bind with a spacer, again most of us. However, spacers do add pre load on the springs. For those that don't know what preload it, it's the compression of a spring at ride height. So essentially what you're doing is keeping the spring under constant load it wasn't designed for which CAN cause premature wear. That said, there's no reason one couldn't do what I'm doing which is using a HBS leveling spacer, 2" and getting Fox shocks designed for 2-3" lifts front and 1" rear. This will give you a decent level, correct shock length with the ability to swap in new springs down the road which I plan to do.
Just to note, companies will often have different views on levels/lifts and their requirements based on height due to their springs lifting at different amounts and also keep in mind they're businesses designed to make money. Just because you CAN do something, doesn't mean you SHOULD. What I mean by that is sure you can lift 3" without drop brackets and probably have no issues. But at that height, you SHOULD have radius arm drop brackets to restore factory settings. The bigger the angle on the radius arm the less your springs and shocks absorb a bump. All that energy is sent thru the radius arm into the frame and causes a jarring ride. You want radius arms and control arms in general for solid axles to be as flat as possible at ride height to ensure the most compliant ride.
Track bars will also keep your axle centered and prevent wandering and death wobble. As you lift the front axle, the factory track bar will pull the axle to the drivers side slightly. Higher you go the more it shifts. This effects your scrub radius which is the angle between front and rear axle. You want the scrub radius to be damn near perfect for obvious reasons. But you can see that lifting/leveling has a **** ton more things involved then just height. All this should be considered when you're deciding on what way you want to go.
Hope this helps some people understand the recommendations of others and why certain things are more important than others.