all ports can be connected, each individual port can generate 10Gbps, but not all ports concurrently.
Statements are just there in case you really expect to use the full 10Gbps and actually need the full 10Gbps in a guaranteed way.
Since a lot of servers can be connected at 10Gbps, but they are not continuously needing the 10Gbps, the oversubscription should not be an issue for most environments.
If you are pretty sure only 2 servers need full 10Gbps and the others are more modest users of the network, you could still connect them all to 1 module (respecting full10G server1 on port A1, full10G server 2 on port A2, this is based on the channel allocation, and distributing the other servers).
Use a network monitoring tool to closely monitor the interface stats. Better: perform a POC to verify the setup and measure what you need.
Unless you have an all-flash iSCSI system, not many iSCSI arrays can actually achieve 10Gbps...
If it is really critical to get wire-speed, you could consider a move to non-blocking switches,
best regards,Peter