Vaguely on the topic of queing I noticed this year on black Friday several sites had queue systems ( e.g 'game' store was one I remember and even had a limited

Vaguely on the topic of queing I noticed this year on black Friday several sites had queue systems ( e.g 'game' store was one I remember and even had a limited time you could spend on the site after the queue ). Part of me wonders whether this was really a server capacity issue or there was some sort of psychological gaming scheme for customers to feel like they need to make a commitment to purchase. Does anyone have some information on this sort of tactic if so?