This question already has an answer here:
In various episodes (such as Voy: State of Flux) 'transporter sites' appear to be used for transporting people to and from planets.
Is there any particular explanation for this? From other series, and other episodes of the same series, it appears as if site-to-site transport had been perfected by that point and was no longer a formal requirement.
Based on the linked question/answers, seems that the most likely relevant explanation is one of time efficiency?
Within the context of the specific episode, the (large) away team was not in immediate danger. Emergency transporting each individual would have led to a slower total transport time (since locking on each signal and performing the transport would be slower), probably be more energy-expensive, and also riskier (since all calculations for the designated transport site would have had time to be optimized in advance).
[Still seems rather a convenient plot device for the episode, but maybe not as terrible as it seemed on first pass]