I think I explained in the past why I use substack for my guides...
I could host them on my own servers, own domains, but I do not want that (yet). I manage several private domains, but those are private. Nothing related with "DarthCoin" on internet.
Substack is very easy to share and write newsletters. And I don't give a shit if tomorrow they will shut down. Are just some damn guides, that are already backed up on my drive.
When SN will create special subsection for these kind of things, I will move them to SN. Until then are just fine on substack.