As an example, here's a video off my twitch showing how fast the S+ rank died...
https://www.twitch.tv/videos/1225690070?t=00h03m00s
Exactly one minute. Reminder this is supposed to be an S+
The minion scaling makes sense because you have a set time to engage them and have to split the attendees into four groups, so killing them in time during low attendance times (which won't be for a while anyways) was a problem before, but I don't understand why, in the minimum ilevel gear, they're melting this quickly.
In comparison, here is an S+ spawn with similar attendance numbers at the start of SHB, lasting about two and a half minutes
https://www.twitch.tv/videos/449419700?t=00h04m11s