First of all, we should admit that now Bitcointalk isn't same as it was 5 years ago. Traffic and activity is declining.
But the quality is increasing. There's still bounty spam, but the Merit requirements helpt. That's visible in
this topic: 6 years ago, the number of posts dropped by 65% in the months after Jr. Members required 1 Merit.
You have a point though: after that reduction, the forum saw 124,306 new posts per week. Now we're down to
23,443 posts per week. Now compare that to the 353,813 posts per week before this change (and it was probably even more than that before I started keeping track).