Interesting. I occasionally got that feeling from TNG, more often from TOS... but I really didn't get it here. The Shinzou was on the "edge" of Federation space, near disputed territory... yet they had no problem consulting in real time with an Admiral, or even with someone on Vulcan in the heart of the Federation. What's more, when trouble arose, a dozen or so other starships were mere hours away, and even capable of timing their arrival to warp in simultaneously for maximum dramatic effect.
None of this adds up to the impression that was so commonplace in the TOS era — that starships are few and far between out there, and the captain and crew of any one of them are usually on their own, responsible for resolving the situations they encounter without backup.
Instead this episode left me with an impression that I also got from the JJA films, and it bothers me here as it did there — that the writers have forgotten that space is really, really BIG.
I think TOS pulled that feeling off by really being FAR off in unknown space. This episodes (and the JJmovies) take place on or near home turf. As did many episodes of TNG, but even some TOS ones.
Considering the type of story (war arc), I'm not betting on getting that "out there in the wild"-feeling anytime during the first season. I hope that once this klingon story arc is finished, the Discovery will also fly far out into the unknown, without backup. Akin to what ENT did during season 3, but hopefully with a more optimistic mission statement.