The lack of "deep content" or "threadooors" in the Arena is a problem that is not readily solved by implementing a single feature (e.g. social logins). You can feel this is a serious issue when most of the feed is just one-liners, shitposts, and "GM" posts. Even the "trending" tab has reverted back to promotions, giveaways, and Arena announcements. There isn't much of a reason to spend more than a minute on the feed.
Certain features (or lack of) cause deep written content to be deprioritized. Long-form content getting hidden by the "show more" cutoff is actively dissuading threads. Lack of robust thread editing, limitations of cross-posting long posts to X, single image insertion into posts, and lack of support for "articles" in the Arena are very limiting for serious writers. A history of broken link backs to posts show that the Arena simply doesn't care for evergreen writing. Modules for "Live" content and trading activity in the UI showcase everything except written content.
Threadooors and long form written content creators will come to the platform when there are incentives to produce content that reflects the effort needed to make such content. As long as this platform has existed, there has been no real difference between short/medium/long form content on the feed. When viewed in the lens of likes/reposts/comments/bookmarks/tips, the return on time for long form content in the Arena is abysmal (I know from personal experience). Writing good content has very low relative returns and it will take specific focus on promoting this from the Arena team for it really be attractive for threadooors to participate in a meaningful manner.
The focus of the Arena right now is on live streaming and the trenches, and I do not see that changing anytime soon.