From the wikipedia, it gives the following reason
Move to 802.1 layer in 2008[edit]
David Law noted in 2006 that certain 802.1 layers (such as 802.1X security) were positioned in the protocol stack above Link Aggregation which was defined as an 802.3sublayer.[5] This discrepancy was resolved with formal transfer of the protocol to the 802.1 group with the publication of IEEE 802.1AX-2008 on 3 November 2008.[6]
I not so sure about the description above, if LACP belongs to 802.3 working group, 802.1x above the 802.3 stack, so it can treat the LAG ports as one port to do the access control, what's wrong with my description? It seems the 802.1x should stand below LACP from the wiki description, can someone explain why the relationship between them should like that?