I agree with those two statements, and the context of your statement makes me think we're talking about two different things:
.5 alignment is a way to control the dispersion of your cabinet so that it sounds the same in more places on stage.
It's often employed in "full range" cabinets (that strive to recreate "every frequency that comes off my strings") but it's not the same thing.
Think of a good old-fashioned 2x15 cab -- it's going to sound much more consistent on stage if it's standing vertically, rather than horizontally.
Yes, my 410 cabs had tweeters, but .5 Alignment would also be a great way for tweeterless 410 or 412 cabinet to disperse more evenly, so that killer sound you dial in standing right in front of the amp doesn't completely change when you walk over to the drum riser.
Basically, it'd allow Hiwatt to build traditional looking cabinets that behaved better onstage.