As the only card of this rarity in the set, it's clear that this card was deemed the most sought-after in the set and the hardest one to pull from a pack
While youre free to run as many attraction support cards as you desire in the 99, it certainly doesnt feel obligatory to include them in order to get your moneys worth out of this commander
Edit: The context of these citations is also important and lends to the way the sources are working in the text

There are 100 cards in this set: Set List & Scans Scan Cards for Trainers to battle in Mossdeep and the Battle Tower aswell as adding some brand new berries to the game: Scan Cards into Colosseum to add new trainers with Dark Pokmon that you can steal aswell as a New Stage: Scan Cards into Pokmon Channel with the GCN-GBA link cable to unlock new pictures and other goodies: Scan Cards into Pinball R/S to increase the ratios of finding Pokmon...and many more!: The First Pokmon Card Set with Dot Codes on, on all cards but holofoils, there is a small barcode containing card details and sometimes Pokdex Info, on many others there are programs or part of Programs Including Mini-Games, Sounds and Animations: The Second Pokmon Card Set with Dot Codes on, on all numbered cards, there is a small barcode containing card details and sometimes Pokdex Info, on many others there are programs or part of Programs Including Mini-Games, Platform Game Blocks, Sounds and Hidden Attacks!: The Third Pokmon Card Set with Dot Codes on but the last made by Wizards of the Coast, on all numbered cards, there is a small barcode containing card details and sometimes Pokdex Info, on many others there are programs or part of Programs Including Mini-Games, Platform Game Blocks, Sounds and Hidden Attacks!: The First E-Card Set Made by Nintendo, unfortunately these cards are devoid of all the extra-stuff in the 3 Wizards sets, all the non-holographic cards have small barcodes on containing Dex Info and Card Information: The Second of the sets released by Nintendo, these cards also only have Dex info and card information on the dot codes

Thats from both review openings and my own personal purchases - I must be closing in on 500 packs with no special art cards
The more you build to empower the Cradle the more this is the case