Who else then? The Illuminati? Yeah, they gathered them together for safekeeping, but immediately redistributed them one by one to keep their powers separate.
You didn't read my post at all, did you?
The Collector doesn't collect "things," he collects *beings.* Aliens, superheroes, what have you. Unless you believe the Infinity Stones are living creatures, that doesn't fit into his particular fetish.
And it alludes to him being *Thanos,* because *Thanos* is the one guy in the MCU who actively collects Infinity Gems/Stones, for the sole purpose of combining their powers into the unstoppable Infinity Gauntlet.
Maybe The Collector just works for Thanos, but given BDT's prominence as an actor, and his assignment to multiple films in the MCU, I just don't believe that Marvel would waste his talents on a supervillain's henchman, when those talents would be much better served as the supervillain himself. i.e.: The Supervillain of All Supervillains. The Mad Titan. Thanos, by name.