Maybe they didn't get the "memo", because a number of local churches thought that the First Letter of Clement was Scriptures - which is why they proclaimed it during the Mass. The idea of "canonization" didn't occur until the late 300's as a result of NOT KNOWING which was without doubt inspired by God. Otherwise, what would be the need to officially set down the Canon if it was just "known by everyone"?
Regards
Maybe you didn't get the memo, there was no 'Mass' for the first centuries of Christianity.
There were many false books competing with Christianity, but the local churches were able to filter them out.
In the later centuries, it was recognized what had been mostly accepted by individual churches.
False churches accepted apocyrpha books in both the Old and New Testament.
Ever figure out what Jn.15:2 means?