True, but perhaps normal fissure missions should be the more efficient thing to do for solo or duo players, DE did intend for railjack to be team focused. Idk, it just seems like an easy and simple implementation while a lot of other suggestions for cracking multiple relics seem convoluted to me, both in terms of gameplay and implementation. That being said, perhaps there is a better way of implementing cracking multiple relics that I haven't seen or thought of.
Why not make it so that you get a reward from each opened relic instead of choosing one reward. For example, if you have a full team of 4 each with a relic, you get all 4 items instead of choosing 1. This seems like the simplest way to handle cracking multiple relics.