p2p – What is the purpose of the version field in the version messages exchanged during connection setup?

I thought that when two nodes connect, the version messages exchanged and the version fields within them indicate what each node supports. Each version supports some new features, and depending on which version these messages are exchanged between nodes, smaller versions of the protocol are used, and each node knows what it can “ask” of the other nodes.

But based on this and the comments:

Protocol version 70014 simply means: sendcmpct The command exists, but compact blocks are not actually supported.

…I think my assumption is wrong.

So what is the purpose of the version field in the version message?