Indeed, there are regular numbers of arriving pilgrims each day who choose to only receive the Cathedral sello or stamp indicating that they made it that far. Absent a Compostela, that is the only thing the sello signifies. However, for some travelers, that is sufficient.
People opt for this for varied reasons, including: they already have a Compostela from a previous pilgrimage and do not want another one; they were not on pilgrimage for a religious or spiritual purpose and only want the sello to indicate they made it to the Cathedral Pilgrim Office; or they are not yet finished with their Camino, perhaps planning to return after they walk round trip to Finisterre and Muxia, they just want the sello as a way point in the same manner as all the other sellos.
When I worked as a volunteer at the Pilgrim Office last June, we would try to identify these folks waiting in the queue. Once both we and they understood that only the sello was desired, we either applied a stamp / sello if we had one on the queue, or we walked these people straight into the office to apply a sello. We then asked them to exit directly ahead, through the Cathedral tienda (gift shop) to prevent the other folks in the queue from getting the wrong idea.
Clearly, it was better for all if we had a stamp outside and could prevent the appearance of preferential treatment - which this is clearly not. It just does not make sense to ask someone who only wants the stamp of the Cathedral in their credencial, to wait for possibly a couple of hours in a queue, when the matter can be settled in 10 seconds, outside. So, we just handled it.
So, if you arrive at the Pilgrim Office and decide you ONLY want the Cathedral stamp / sello in your pilgrim credential, please, either ask a volunteer or other employee who might be working the queue outside, or approach the security person at the entry to the Pilgrim Office and tell them that you only want to get a stamp. The simple Spanish for this is "Sello sólo por favor" (Stamp only please). You will be accommodated promptly. It serves everyone's purposes to try to maintain the queues as short as practicable. This is one way it is done.
Just FYI, the other way the Pilgrim Office tries to attenuate the queues is to handle larger groups of pilgrims offline, at a separate location. The group leader submits all the necessary paperwork and credencials for all the persons in their group to the Pilgrim Office management. One Pilgrim Office employee or a volunteer processes all these Compostelas offline, in a back room. They are delivered, without ceremony, to the group leader.
This might sound like preferential treatment. However, consider the effect on a daily queue that is already long, if several groups of a couple of dozen pilgrims each (all with the same basic story, starting point, motivation, etc.) are made to remain in the queue. It reminds me of a giant clog in a sink drain. I am sure you understand.
Further to this, I understand informally that, concomitant with the planned relocation of the Pilgrim off to the Rua de Carretas (down the ramp next to the Parador, first right, then about one street down on the left), there may be some improvements to the process that might further expedite queues and mitigate the wait times. I do not have the new address. Neither do I have more specifics about what process changes are planned, if any. I am sure someone will make that information available at the appropriate time.
I hope this helps.
