I'm not sure what you're basing these opinions on, but I'd have to disagree strongly. I've been on Althanas for years and years, and there has always been times when quality of writing takes a back seat, even back in the day when every single completed thread received a full rubric judgment. Every so often there'd be an event that offered 2x EXP or something, and suddenly people who ordinarily scored 65+ would be scoring low 50s because they were churning out threads as fast as possible. The difference is most threads don't get judged now, so trends in quality of writing are less apparent.
And power leveling is not the only reason quality of writing sometimes takes a back seat. Sometimes people just want to blow off steam, or have fun with a unique idea. I'll cite one of my own threads from 3.1 as an example:
The Flesh Failures: Empty Orchestra
The above linked thread is the most recent in a string of themed threads I hosted over the years. The purpose of these threads has always just been to mess around and have fun, and I can tell you with absolute certainty that my quality of writing took a back seat to silliness in this thread, and others like it.
To address your other point, if someone is pumping out speed threads or just blowing off steam and being silly, they are by definition
not making mental notes for improvement. To make an analogy, you don't get better at baseball by holding a bat any way you like and swinging it around randomly. You get better at baseball by holding the bat properly, and taking a proper stance, and swinging at an appropriate sized ball approaching at an appropriate speed. In other words, to quote and/or paraphrase apparently Vince Lombardi, "Practice doesn't make perfect. Perfect practice makes perfect". This basically just means that in order to see significant improvement in a skill, you need to deliberately try to get better at it, not just participate in it for enjoyment and/or breeze through it as quickly as possible.
For me, Althanas has always been mainly a combination of the first two poll options, with the addition that it has always been a place of learning and teaching, and with a little of the other options thrown in for flavor. When I first came here I was a young teen with literally no concept of how to craft a character, or a story, or properly describe a scene. I remember scoring something like 33/100 on my first ever thread, and the judge was none too kind with his remarks. Now I see Althanas as a place to sharpen my skills and give back to the community through mod work and workshops. I also see it as a place where my quality of writing sometimes takes a back seat to having fun and blowing off steam, or power posting, and I personally didn't feel like Shin was looking down on me for this, or being aggressive or whatever.