Probably not a popular opinion, but here goes.
Those Okri’s Challenges were the only season 1 exclusive rewards. All the portraits released during season 1 are in the general WoM tab, the leaderboard rankings got deleted, rewards for being high up on the leaderboard got scrapped, and the weave progress got reset (except for weave 1-40, which you have to play regardless in order to get that 1-40 portrait).
Take those Okri’s Challenges away, and season 1 would have been completely pointless in terms of rewards. You might as well have not played during season 1 and waited until season 2. This would be pretty unfair for those who actually played during that season, especially considering how difficult season 1 was compared to season 2.
And since seasonal Okri’s Challenges do not show up on the summary screen in the book, you can still have it say 100% completion even if you did not do any of those challenges.
But there should be some kind of indicator to show that you cannot complete those challenges, to avoid confusion.