I'm Cardcaptor Sakura it is known that Clow Reed created the Clow Cards and then set up an entire infrastructure to seal them until until Sakura could get to them because they were so powerful. It's been a while since I've read the manga or seen the show, and I'm wondering: why did he create the cards in the first place, particularly if they were going to be so much trouble to deal with after the fact.
I don't know the exact reason why Clow Reed created the Clow Cards. however i belive that they weren't created solely for the purpose to give to Sakura.
Cardcaptor Sakura is apart of a greater Multiverse in which other CLAMP Titles such as Tsubasa RESERVoir CHRoNiCLE and xxxHolic are set in. in that multiverse Clow Reed is known as the greatest magician of all time and one of his abilities is Prophetic Dreams
Clow possesses the powers of a Dream Seer, allowing him to see into the future. However, unlike most other characters, who could only see fragments of the future, Fei Wang stated that Clow can see everything, which gave him free reign to control events, hence how he had managed to foresee Sakura collecting the Clow Cards, making him create a Sealing Wand of the color pink for Sakura being a girl. He even knew that he would, as Eriol, cause problems for her to help her create Sakura Cards.
ofcause if he foresaw Sakura sealing the cards and made the Sealing Wand specifically for her why did he let all that happen in the first place? the reason was that when he neared his death he had chosen Sakura (who had yet to even been born) to succeed him and most of it was by design.
When Clow was nearing death, he chose Sakura Kinomoto to be the new mistress of The Clow. Sakura was not yet born at the time, but Clow's magical ability allowed him to foresee most of the future and plan many of the situations that would enable Sakura to succeed in taking full possession of the Clow Cards. The reason why Sakura's wand is pink is that he wanted to make a suitable wand for the young girl who would be mistress. It wasn't because of chance that Keroberos chose Sakura.
as such the seal on the Clow Cards, while it did lock away the powerful magic that was the Clow Cards, it was only until it was Sakura's time to claim them and thus the reason why the book was in Sakura's home and not in Li's who is a blood decedent of Clow Reed.
The reason why i say that the Clow Cards weren't created just to give to Sakura is that in the first Cardcaptor Sakura movie Su Yung/The Madoushi, a former apprentice and lover of Clow Reed, was sealed inside the Book of Clow until Sakura unintentionally released her. while it is possible the Cards were created long after the Book of Clow considering the book's magical independent uselessness after the cards were released i would think that both the book and cards were created at the same time.