I think there has been a tightening of the eligibility criterion of 'must be expert in'.
Coincidentally (not in fact a coincidence, I suspect), the new head of Boost has pubbed a piece today inviting academics to come and write on Medium. No bad thing, and the names she cites who are already here include some really good, interesting writers.
But I think overall they are aiming to address the phenomenon of 'anyone can sound off about anything online and no one knows whose opinion or info to trust' by sticking to that 'if you ain't got a PhD in this, you ain't getting boosted' philosophy.
There's a big problem here, in that - as I said to them in feedback - knowledge does not mean wisdom, and 'non-experts' often have insights that narrowly focused experts miss.
'Consultant nephrologists see everyone as simply a pair of kidneys, not as people, much less members of families and society' was the line I used.
I got my recent piece about translation boosted, which didn't surprise me as they 'know' I am a qualified, experienced professional in that niche (unless I'm just bullshitting, of course - no one's seen my diploma...).
But I also had two of my typical 'views of language, culture, society from the guy in Spain' pieces nommed but nixxed at the end of last month. Now, those were pieces I would have felt very confident about, as I thought that was also an area where I had 'approved' status, based on previous articles, and my ownership of the pub.
I've submitted two more in those areas today to pubs I expect to nom them. If those two also get shot down, that would suggest that it's now 'professional qualifications or nothing', unless it's actually personal sob story memoir.
If at least one of those 2 pieces is boosted, then that window remains slightly open, otherwise I will have to shut that down as well, as I have now done with 'music', and only my translation/language stuff will ever be boosted, so I'll just trot out a couple of those per month. Stuff from the pub is mostly being rejected as well - I had one pub nom accepted last month, I think, and 3 or 4 that would have been picked back in May/June were rejected.
We shall see...