Off topic, but I wonder why the author is using _both_ Substack and his old website [1]. Is this a new trend?

[1] https://simonwillison.net/2025/Sep/6/research-goblin/

I use Substack as a free email delivery service - it's just content copied over from my blog: https://simonwillison.net/2023/Apr/4/substack-observable/