Adding on, there are still things to be learned from junior developers.
Given how many resources there are for senior developers to have a large audience, I'd go so far as to say it's good for junior developers to have an audience too.
The trick is, to keep the new genration of devs in the community while they become seniors.
I think a huge side effect of the focus on being welcoming is that it attracts a lot of juniors. The more beginner-focused stuff also tends to bubble to the top out of popularity, but over time I really hope we can improve the algorithms to be the right relevant mix of content for everyone.
Almost by definition, these things take time. We can't rush it, but I think the platform will eventually host the kinds of deeper, more advanced articles and discussions a lot of folks are looking for.
It will happen as we improve platform mechanics to serve different user groups effectively, but as you mentioned, it should also happen naturally as folks grow up on DEV.
I think that having junior devs around is hugely insightful actually. As devs we often get tunnel vision and do things simply because we always have. Having somebody question why is often a learning experience in itself because it makes us stop and think "Yeah...why do I do it this way?" Which makes us better. Dev.to is my favorite programming community as well mostly because people share their stories. The rest of the world sees us developers as robots that write code and nothing else. It can be kind of depressing when your contemporaries also forget that you are a human being.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.