This overlooks ProxyCommand, the single most useful reason for using an ssh config file.

e.g.:

    Host internal-*.example.net
        ProxyCommand ssh -T external.example.net 'nc %h %p'

Basically, specify as ProxyCommand whatever command needs to be run to give you i/o to the remote sshd - in this case, sshing to a bastion host and running netcat. This allows me to do, for example:

    ssh internal-dev.example.net

Which will (in background) ssh to the bastion host external.example.net. I can even do port forwards to internal hosts using -L or LocalForward directives. It's a huuuuge timesaver.

ssh even automatically replaces %h and %p in the ProxyCommand with a host and port, though you can of course replace those tokens with static values if it works better.

(Also, note above that one can use wildcards in Host declarations.)