Sorry, I think I misunderstood the question. I agree that it would be nice to reply and make drawings on Juxt using a browser!
To answer the other question,
Yeah, we actually already do that. Trying to sign into the Juxt website before signing in on a console shows the error “Account Creation is only available when you have a linked Wii U or 3DS.” You can’t even view posts without linking a console first.