VG have 5 entities so not that standard.
Riflemen are also 5 entities yet the paras is the only USF unit with 6 entities. The reason behind that is that aggressive airdrops are hazardous. Entities might hit world object and die or can be shot down before they land die.
If paras are not used aggressively the hole mechanism become less important.
That is factually incorrect and a wrong misconception of the game's mechanics. The reason is simple, and I'll keep it short for you: There are other units (example: Falls) that follow the same idea of an aggressive airdrop or infiltration as Paratroopers. Falls are factually even more aggressive due to their innate abilities and their ability to drop as good as anywhere safely due to their fall pattern but they have fewer models. Meanwhile, you have to learn and understand where to use the Paras for them to drop and land safely. It can be behind enemy lines but there are not that many non-obvious spots for them to land on most maps (easier with pathfinders tho). Falls are definitely the better due to their even more aggressive drops, less chance to lose a model on landing (landing pattern), quicker drops (again less models), and has endless great spots on every map for good play. There is no hole mechanic, I assume you had a typo and you mean "whole".
Edit: I spotted that sander, who knows the game in and out, is of the same opinion.