Looking at the chart on the referenced post, the 1 merit for Jr. Members introduced in mid September 2018 did not seem to alter the trend at all (number of posts per month), but rather continued its downward pattern, which, as expected, is in consonance to market (see for example chart comparison on re: Bitcointalk is Dying?).
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The way I see it, Bitcointalk seems to be rather aligned to how Bitcoin/cypto is behaving currently. That is natural and rather much unavoidable.

ABSTRACT
(1) 50% of observed months have intra-month registered account range from 2311 to 27790 (the interquartile range);
(2) 50% of observed months have intra-month registered account above or below 10432 (the median);
(3) The intra-month registered account fell 91.6% from its all time high in 2017 at 238400 to 20046; whilst the bitcoin decreased nearly 83.9%.
(4) The demotion on Junior Members in September 2018 probably caused intra-month registered accounts fell considerbaly later months.
(5) The difference in means of before and after periods (cut-off timepoint is Sept. 2018) is -63.6%.

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Time-series plot