I'm not sure that tells us very much, the field has changed a lot in the past 110 years. Would other papers of the time be rejected today also? He could have been on par with his peers.
I don't think it was his thought experiments so much as predicting the precession of Mercury's perihelion that got everybody's attention. "You have a vivid imagination? We all do, kid." And then "You figured out the Mercury problem?!?!? Tell me about those thought experiments again?"