Medium - how does it work? Is it worthwhile?

Medium is a website where you can write whatever you want and publish it like a blog, or submit it to a 'Medium Publication'. If it's accepted, the publication will publish it on their platform for better visibility. You then get paid for reads and claps by paying subscribers. The rates are low, but if you get a lot of reads and engagement, then it can pay well, so I hear anyway. I have yet to experience this delight.

Why 'Write What you Want' isn't my favourite philosophy...

Whenever I ask the writing community on Twitter about lucrative book genres, best selling topics and market trends, I get some helpful responses. 

Then the "write what you want!" crowd wade in, with the message that writing for market is somehow unethical, wrong, and doomed to failure because it's not necessarily your first choice of subject. There seems to be a view that it's detrimental to the creative process.