A card is black if and only if it is the ace of spades.
There are other conditions under which B (a card is black) can happen, so the second statement is not true.
A conclusion that would be correct is "If a card is not black, it is not the ace of spades.". The condition is that if A is true B will also always be true, so if B is false we can be sure that A is false as well - i.e. "If not B, not A".
I'd say the difference is convenience, brand recognition, and social media features.
You only need to sign up to Substack and you can already start publishing, so the vast majority of people who just want to write and not have to bother with building their own website will opt for the simpler option. Even if it takes only a handful more clicks to publish a personal website, the very idea of having to build something will be daunting enough to turn off most people.
Then there's the fact that while many people are willing to sign up to a well-known website like Substack, not that many are willing to enter their email into some random blog. I'm willing to bet that if some famous online personality made their own website+newsletter to publish their writings they'd get a lot of responses along the lines of "Who cares for antiquated personal blogs nowadays? What is this, 2005? Just make a Substack!"
And while the article presents Substack's social media features as a possible negative, the idea that anyone could see your post if it pops up in their frontpage, or that you might be the next lucky writer to get noticed by the algorithm and be recommended to thousands of people, will certainly be tempting to many.
In the long run machines are cheaper (also don't take days off nor try to unionize), which is why many companies are looking to automate things with AI or just robots in general.
In assuming that it's simply impossible for a machine to accurately follow the same process as a person and make quality coffee (in his own subjective judgement), @makingStuffForFun sounds much like wine snob to me.
Literally. From a report by the Treasury Department:
Unionization also has spillover effects that extend well beyond union workers. Competition means workers at nonunionized firms see increased wages too. Heightened workplace safety norms can pull up whole industries. Union members improve their communities through heightened civic engagement; they are more likely to vote, donate to charity, and participate in a neighborhood project. And, the higher pay and job security of both union and nonunion middle-class workers can further spill over to their families and communities through more stable housing, more investment in education, and other channels.
Tangentially related meme: