BMS isn't as prophetic as Maoyan or Egg but a good measure for most movies. It get spammed at times but still fine.
Also, if BMS has a bad score, that means the WOM is certainly bad. But a good score is open for interpretation.
As for Mass thing. It is generally to convey the type of content that reaches enmasses. Generally masala action is what reaches everywhere. Thor having that image, especially thanks to Wakanda entry & Ragnarok is more mass hero than say Black Panther.
Thor is only second to Tony in a recent survey by Ormax
https://twitter.com/OrmaxMedia/status/1539953439488282625