It does not defeat the point of the attack.
NA / SA form an alliance 99 % of the time. And Africa ( almost ) always goes for EU / SA. Only EU left to have the first hits on NA East Coast.
About Navy on USSR / Africa, if you'd have read my previous post you'd have known that one should;
- Use subs to launch on USSR as soon as you enter defcon, you WILL get the first hits. A few seconds before those nasty subs in the Gulf hit Moscow.
- Have a shitload of bombers going for Cairo. Timing is very important as we all know that Cairo is never defended and Asia / USSR always try to get there before EU.
This way you'll only have to fight off 1 navy ( USSR ) at the start instead of, worst case scenario, 3 when going for the Atlantic.
Now, about "your" tactic. It can be used with EVERY continent as soon as people find out how to actually play and use those blitzkrieg tactics. It's just a mather of hitting the major cities first. It's nothing new and refreshing, and I think it has been discussed here before... The early launch tactics.
Give it a bit more time and this tactic will be highly ineffective due to the fact everyone is going to use the early launch tactic. Then it'll be back to the offensive navy fights and keeping your silo's hidden as long as possible to unload them just in time.