Syncing is slow, because the transfer rate of the node connection is small.
The issue here is, if someone is synced there is no personal benefit to provide a good upload speed.
The opposite is true, more unsynced nodes means a higher winning chance.
Looking at that list shows how many are not Synced by there block height. There clearly is a problem, I am sure there’s a good number of farms that are sitting there doing nothing because the sync process cannot keep up.