This can be gold long-term, though ironically I do see a risk of overcomplication for noobs today. Right now the zeitgeist seems to about making onboarding as simple as possible.
In All Follows, I gotta be honest and say I miss almost all o fit. I view the feed for a few minutes at a time, catching some recent history, then reply or post. I do use kind:30000 lists so in the context of a very small one of those, I could see wanting just the linux posts.
Profiles are more niche. I visit these mostly when someone follows me or makes a meaningful reply. There I'm trying to get an overview of who they are so I like to see everything though if they had 2-3 subprofiles and I wanted to follow them, I might follow a single subprofile or exclude one right at the start. Long-term however I can see this being much more valuable as interests drift but say I still want to get your linux posts.
Really interesting idea altogether. I've thought of this as "channels" and created a Bitcoiner account to try to do this but as a separate account it doesn't really work. A dropdown or tag on each post could work!