I'm bias, as I don't usually write more than four stories a month - although I used to.
I think you need to be consistent sure, but focusing on quantity over quality is a poor approach imo - it could have made more sense if their threshold was based on something like minimum 50K reads per month maybe? Or a strong view/read ratio maybe? Or even readtime/month?
All of those seem to be stronger indicators of the quality of said author rather than article volume no?
But anyway, curious to see this, I haven't heard of anything other than the new reader referral program they're implementing, for those of you interested - from their email:
"Now there are even more ways to earn money on Medium. Introducing Referred Memberships, where Partner Program writers (that’s you!) can refer dedicated readers to become Medium members.
Here’s how it works: Every time you convert a reader to a paying member, you get half of that reader’s membership fee, net of standard payment processor fees, for as long as they are an active member. Referral earnings are additional to existing Partner Program earnings, which are based on member read time. Readers can sign up on your personalized referrals page."