Yes, but le-pig, those horizontal packs are unfashionable as long drops. These people are probably only speaking from experience/ enforcing fashion rules. One can't really comment on a pack one hasn't used.
In practical terms, a horizontal pack might cause a slightly larger profile compared to a vertically oriented pack because the pods removed from a vertical pack marginally decreas your side profile over the course of a game. Horizontal packs stay more or less the same width.