Your post quality depends on what you write, not on your rank. A newbie with deep knowledge can write super quality posts, better than a Legendary member with a shit post. I have to mention that before the Merit system kick-off in January 2018, forum members could rank up easily (no merit requirement). Many old members with high ranks before appearance of merit system are shit posters.

Members with same earned merits can have difference in post quality. You can look at The future of Bitcointalk: Low Ranking Top Merit earners in the past 30 days and see differences in post quality of those low rank members.

What you see as nonsense might make sense to others; you can't just conclude the complete meaning of someone's statement based on your own personal point of view. Here in this forum, everyone is entitled to their own ideas; you can't contribute more than you don't know.