It's relatively rare for someone who has spent a long time playing to respond a Low Rank SOS because of two reasons.
One, Low Rank isn't really that long compared to High Rank, so not many quests are posted and consequently not many people will be looking for them when searching SOS (you have to chose either of the ranks when searching).
Two, as you said, it feels like your are crashing the party of someone and taking away all the fun they were having. That's why, the very few times I respond to LR SOS, I wear an armor that is geared 100% for support and bring a Hunting Horn so most of my time is spent healing, buffing and sometimes going for a KO or paralyzing the monster instead of going for damage. Typically, this would not be the right way to play the Hunting Horn but in this instance it's the best way to not ruin their experience while still helping.