Nothing quite replaced Dr Dobbs... Hacker News offers random links to the kind of technical articles that Dr Dobbs used to have, but of course - for better or worse - it's a lot less focused.
DDJ was just affirmational, “here is some knowledge” “here is how I built <x>” there is an innocence to it. You might ignore it, that knowledge might alter your career. It was a neat magazine of people doing cool stuff in areas I’m interested without the baggage. Just possibilities.
Hard or impossible to replace with that scale today.
In the 70s through the mid 90s, before the WWW v1.0 bubble taught the world you could get rich quick in software, there was a greater appetite to, say, take your time working your way through an article on a new technique in C. Now the vast majority of people just want copy/paste Python code examples from Stack Overflow. At most they may suffer through a brief video tutorial.
Part of this is not some “kids these days” sort of reason, but the reality that most code is much more short lived than ever before.