If you turn off the Sky network you have no network, the same with TT, PlusNet, Zen and AAISP
For EE its different as they buy the service from BT Wholesale
Similar for BT Retail all though agreement is different
The question with the resellers is what added value do they add, instead of going direct to who they buy trom.
But I would agree this list does not look like a list of actual FoD sellers, some will do it, but others will probably be looking to do managed installs of FTTC