i'd rather rush sb then rush an embassy, to be honest, to get all the researches you need done for the embassys to really hurt somebody, a starbase might be more effective, as it will end up killing temples on that world.
The point that's being made is that starbases can be countered with low tech solutions. Heck, if you have two factories on your homeworld you can actually fight off a starbase in construction before it finishes by spamming nothing but Cobalts or Disciples. The embassy there is no real way to stop without high level civic techs yourself.
That said, the biggest problem I see with this type of strategy is that if you can't project culture you can't "finish the job". This would be a great way to finish off someone who is turtling up around a starbase, but not so much a way to turn back an aggressive attacker, since you probably can't get close to his homeworld with culture anyways. At worst you can knock his income a bit, but he can always receive feed to counteract this.
bugs galore, no MP fun
It's a beta, they fully acknowledged that this would be the status for the first while.