I hear a lot of people (coaches and athletes alike) state: "You can't win a triathlon in the swim, but you can lose one in the swim".
I've heard numerous athletes declare: "I just need to survive the swim".
I disagree with both statements. As a coach these are the first things, should an athlete of mine say such a thing, that we remove from the conversation. You can indeed win a triathlon by having a good swim. Just as you can win it by having a good bike, or run. But you have to be strong across all the disciplines to ensure that your good swim effort holds up at the end.
Just surviving the swim? That's a great way to lose time, waste energy, and ensure you have a harder bike and run leg than is necessary.
In regards to the sport of triathlon every discipline is important. Wasted energy on the swim will impact you later in the race - not only being more fatigued on the run, but adding to your overall time. Having a weak bike leg is time lost that you must make up on the run. Or, of course, being a weaker runner requires more effort on the swim and the bike.
Instead of making concessions you should work on your limiters. Going back to the original premise, if you're not a strong swimmer you should work with a coach to ensure that you are as efficient as possible - working on your stroke mechanics and energy systems as necessary. Just as you work on your form and speed on the run and power on the bike, you have to do the same with your swim. Otherwise you're losing time and wasting energy.
And, as a point of reference, my last triathlon race win? Fastest swim. Fourth fastest bike. Third fastest run. So, contrary to popular belief, yes you can win a triathlon in the swim leg.
The lesson here? Work with your coach to improve your swim. Or find a coach who will. Don't accept mediocrity in regards to your swimming.