Well, I can't speak for the average user, but you would be surprised how many enthusiasts actually use all the lanes in their motherboards for I/O.
Want 10Gbit NIC? Want USB4 or at least 10Gbps ports? Want RAID5? Want a small homebew NAS? Want more than 4 NVMe ports with add-in cards? And so on and so forth.
In my case, I have 3 NVMes and 3 sATA drives and I ran out of "normal" lanes, so I sacrificed the X16 to X8 and the lane splitting is real.
It's not overblown or a stretch to say AMD needs to pick up the slack for enthusiasts. Intel is not much better. The jump from the regular consumer platform to the workstation is too damn much and they need to close the gap.
Regards.