Buffs gives incentive to swathes of players to sacrifice items. Uncommon, rare and ultra rare cosmetic benefits creates a brand new money making marketplace for those who want to acquire the new cosmetics. Pet chance clearly grabs the eye of hunters who will be the biggest contributors. This way helps to integrate OSRS Gold lore by using the gods & makes more sense than a pit which people bottomlessly throw things into in the GE.
For instance of a buff: Should you sacrifice enough things the Luck of Saradomin is gained by you. This buff would last 24 hours until activated. This buff gives your personality a 75% chance to restore 50 hit points at the case that your character falls into zero HP. After triggered, by committing to the altar, the enthusiast has to be earned again. Buff works on PVM rather than PVP.
Having to contribute things & needing to travel to the altar is from benefitting will prevent bots. It makes serious gamers need to donate higher quality/value things for use. Perhaps a full inventory of addy pubs is enough to find the boon, but cosmetic/pet chance is actually only realistic with large ticket items. Like barrows armor, whips, etc..
Attempting to buy whatever the day's random thing is would be a hellish experience on such day. Also, I see a good deal of sentiment on reddit about the need for Jagex to take more actions to suppress inflation, but no proof that it's actually a problem in RuneScape. Folks underestimate the number of mechanics exist in Cheap OSRS Gold to take money.